Update QT install GH action.

Author: sletz

.github/workflows/libfaust.yml

@@ -1,7 +1,7 @@
 name: libfaust
 
 env:
-  FAUST_VERSION: 2.74.6
+  FAUST_VERSION: 2.74.6
   FAUSTGEN_VERSION: "1.71"   
   LLVM_PACKAGE_VERSION: "15.0.7"
   CMAKE_OSX_DEPLOYMENT_TARGET: "10.15"
@@ -219,7 +219,7 @@ jobs:
       run: brew install pkg-config ncurses gtk+ liblo lame flac libogg libtool libvorbis opus mpg123
 
     - name: Install Qt
-      uses: jurplel/install-qt-action@v3
+      uses: jurplel/install-qt-action@v4
       with:
         version: '5.15.2'
         host: 'mac'