Update to Qt6

- New baseline minimum platform is Ubuntu 22.04
    - Qt6 requires at least 6.2
        - some deprecations may be flagged on later versions (e.g. 6.8)
    - CMake requires at least 3.22
- Include build-tests.yml github action to validate builds on mulitple platforms
- QtTest is no longer optional since it easily comes along for the ride with Qt
- Replaced QStringRef in model::SubstitutionField with simple ParserState class
- Removed deprecations up to Qt 6.2

glabels/CMakeLists.txt

@@ -107,9 +107,9 @@ set (glabels_resource_files
   images.qrc
 )
 
-qt5_wrap_cpp (glabels_moc_sources ${glabels_qobject_headers})
-qt5_wrap_ui (glabels_forms_headers ${glabels_forms})
-qt5_add_resources (glabels_qrc_sources ${glabels_resource_files})
+qt6_wrap_cpp (glabels_moc_sources ${glabels_qobject_headers})
+qt6_wrap_ui (glabels_forms_headers ${glabels_forms})
+qt6_add_resources (glabels_qrc_sources ${glabels_resource_files})
 
 if (WIN32)
   # Windows resource file
@@ -137,7 +137,7 @@ target_include_directories (glabels-qt
 
 target_link_libraries (glabels-qt
   Model
-  Qt5::Widgets
+  Qt6::Widgets
 )
 
 #=======================================
@@ -173,7 +173,6 @@ if (WIN32)
                 env PATH="${QT_BIN_DIR}" "${WINDEPLOYQT_EXECUTABLE}"
                     --verbose 0
                     --no-compiler-runtime
-                    --no-angle
                     --no-opengl-sw
                     \"$<TARGET_FILE:glabels-qt>\"
         )
@@ -198,7 +197,6 @@ if (WIN32)
                     --verbose 0
                     --release
                     --no-compiler-runtime
-                    --no-angle
                     --no-opengl-sw
                     \"$<TARGET_FILE:glabels-qt>\"
         )