Reinstace the Qt6 macOS gcc exclusions

Since every one of those is still affected by QTBUG-107050.

See https://bugreports.qt.io/browse/QTBUG-107050

.github/workflows/build.yaml

@@ -180,16 +180,14 @@ jobs:
           - { qt: '5.10.1', env: { cc: gcc-14 } }
           # Exclude Qt 6.2 on macOS 14+ (Qt6 only officially supports macOS 14 from Qt 6.4+, and some 6.2.n LTS update).
           #- { qt: '6.2.4',   os: 'macos-14' }
-          # Exclude Qt6 with GCC on macOS for now, as GCC (only) has lots of false compiler
-          # errors, that even if worked-around result in SIGBUS errors in unit tests. See
-          # https://bugreports.qt.io/browse/QTBUG-107050 (non-exhaustive).
-          - { qt: '6.2.4', env: { cc: gcc-12 } }
-          - { qt: '6.3.2', env: { cc: gcc-12 } }
-          - { qt: '6.4.3', env: { cc: gcc-12 } }
-          - { qt: '6.5.3', env: { cc: gcc-12 } }
-          - { qt: '6.6.3', env: { cc: gcc-12 } }
-          - { qt: '6.7.3', env: { cc: gcc-12 } }
-          - { qt: '6.8.0', env: { cc: gcc-12 } }
+          # Exclude Qt 6.x with GCC on macOS for now. See https://bugreports.qt.io/browse/QTBUG-107050
+          - { qt: '6.2.4', env: { cc: gcc-14 } }
+          - { qt: '6.3.2', env: { cc: gcc-14 } }
+          - { qt: '6.4.3', env: { cc: gcc-14 } }
+          - { qt: '6.5.3', env: { cc: gcc-14 } }
+          - { qt: '6.6.3', env: { cc: gcc-14 } }
+          - { qt: '6.7.3', env: { cc: gcc-14 } }
+          - { qt: '6.8.0', env: { cc: gcc-14 } }
     steps:
     - uses: actions/checkout@v4
     - name: Install lcov