CI: Remove Qt workaround, update to LTS version on Windows

Author: tstenner

.github/workflows/cppcmake.yml

@@ -58,10 +58,9 @@ jobs:
 
     - name: Install Qt
       if: matrix.os == 'windows-latest'
-      # uses: jurplel/install-qt-action@v2
-      uses: ouuan/install-qt-action@v2.3.1 # workaround until the aqtinstall timeout is fixed
+      uses: jurplel/install-qt-action@v2
       with:
-        version: 5.14.0
+        version: 5.15.1
 
     - name: Configure CMake
       shell: bash