ci: don't use Ruby 2.5 on Ubuntu (#347)

We can't mix newer Psych and old RubyGems/Bundler.


https://github.com/ruby/csv/actions/runs/15464303477/job/43532710831?pr=346#step:3:47

Failed to load /home/runner/.gemrc, wrong number of arguments (given 2,
expected 1)
    Fetching gem metadata from https://rubygems.org/........
    Fetching rake 13.3.0
--- ERROR REPORT TEMPLATE
-------------------------------------------------------

    ```
    ArgumentError: wrong number of arguments (given 4, expected 1)

/home/runner/work/csv/csv/vendor/bundle/ruby/2.5.0/gems/psych-5.2.6/lib/psych.rb:323:in
`safe_load'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/safe_yaml.rb:31:in
`safe_load'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:496:in
`block (2 levels) in read_checksums'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:495:in
`wrap'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:495:in
`block in read_checksums'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package/tar_reader.rb:116:in
`seek'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:494:in
`read_checksums'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:547:in
`block (2 levels) in verify'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package/tar_reader.rb:29:in
`new'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:546:in
`block in verify'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package/file_source.rb:30:in
`open'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package/file_source.rb:30:in
`with_read_io'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:545:in
`verify'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/2.5.0/rubygems/package.rb:526:in
`spec'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/rubygems_gem_installer.rb:95:in
`spec'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/source/rubygems.rb:190:in
`install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer/gem_installer.rb:54:in
`install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer/gem_installer.rb:16:in
`install_from_spec'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer/parallel_installer.rb:186:in
`do_install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer/parallel_installer.rb:90:in
`call'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer/parallel_installer.rb:71:in
`call'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer.rb:254:in
`install_in_parallel'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer.rb:209:in
`install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer.rb:89:in
`block in run'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/process_lock.rb:12:in
`block in lock'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/process_lock.rb:9:in
`open'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/process_lock.rb:9:in
`lock'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer.rb:71:in
`run'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/installer.rb:23:in
`install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/cli/install.rb:62:in
`run'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/cli.rb:257:in
`block in install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/settings.rb:131:in
`temporary'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/cli.rb:256:in
`install'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/vendor/thor/lib/thor/command.rb:27:in
`run'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in
`invoke_command'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/vendor/thor/lib/thor.rb:392:in
`dispatch'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/cli.rb:31:in
`dispatch'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/vendor/thor/lib/thor/base.rb:485:in
`start'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/cli.rb:25:in
`start'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/exe/bundle:48:in
`block in <top (required)>'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/lib/bundler/friendly_errors.rb:120:in
`with_friendly_errors'

/opt/hostedtoolcache/Ruby/2.5.9/x64/lib/ruby/gems/2.5.0/gems/bundler-2.3.27/exe/bundle:36:in
`<top (required)>'
      /opt/hostedtoolcache/Ruby/2.5.9/x64/bin/bundle:23:in `load'
      /opt/hostedtoolcache/Ruby/2.5.9/x64/bin/bundle:23:in `<main>'

Author: kou

.github/workflows/test.yml

@@ -25,6 +25,8 @@ jobs:
           - windows-latest
         exclude:
           - { runs-on: macos-latest, ruby-version: "2.5" }
+          # Can't mix newer Psych and old RubyGems/Bundler
+          - { runs-on: ubuntu-latest, ruby-version: "2.5" }
           - { runs-on: windows-latest, ruby-version: "3.1" }
           - { runs-on: windows-latest, ruby-version: debug }
         include:
@@ -55,6 +57,8 @@ jobs:
           - windows-latest
         exclude:
           - { runs-on: macos-latest, ruby-version: "2.5" }
+          # Can't mix newer Psych and old RubyGems/Bundler
+          - { runs-on: ubuntu-latest, ruby-version: "2.5" }
           - { runs-on: windows-latest, ruby-version: "3.1" }
           - { runs-on: windows-latest, ruby-version: debug }
         include: