Add missing popd in Kivy.app script

[smachave]

Without this change I was getting the following error:

▶ kivy main.py
/Applications/Kivy.app/Contents/Resources/venv/bin ~/Code/Python/kivy_test
python: can't open file '/Applications/Kivy.app/Contents/Resources/venv/bin/main.py': [Errno 2] No such file or directory