Use KF6 with Qt6, to match what qtextpad expects

.github/workflows/ci.yml

@@ -115,7 +115,7 @@ jobs:
           dir: ${{ github.workspace }}\qt
           cache: true
 
-      # KF5SyntaxHighlighting and ecm release in lock-step
+      # KSyntaxHighlighting and ecm release in lock-step
       - name: Checkout ECM
         uses: actions/checkout@v4
         with:
@@ -134,15 +134,15 @@ jobs:
           cmake --build . --config Release -j 2
           cmake --build . --config Release --target INSTALL
 
-      # Build KF5SyntaxHighlighting manually due to Qt dependency...
-      - name: Checkout KF5SyntaxHighlighting
+      # Build KSyntaxHighlighting manually due to Qt dependency...
+      - name: Checkout KSyntaxHighlighting
         uses: actions/checkout@v4
         with:
           repository: KDE/syntax-highlighting
           path: syntax-highlighting
           ref: ${{ matrix.cfg.kf5 }}
 
-      - name: Build KF5SyntaxHighlighting
+      - name: Build KSyntaxHighlighting
         run: |
           cd syntax-highlighting
           mkdir build && cd build

CMakeLists.txt

@@ -30,11 +30,11 @@ if(Qt5_FOUND AND NOT TARGET Qt::Core)
     endforeach()
 endif()
 
-find_package(KF5SyntaxHighlighting REQUIRED)
-if(KF5SyntaxHighlighting_VERSION VERSION_LESS "5.39.0")
-    message(WARNING "KF5SyntaxHighlighting version 5.39.0 or later is required \
-in order to use custom highlighting rules.  KF5SyntaxHighlighting version \
-${KF5SyntaxHighlighting_VERSION} was detected, so these rules will be unavailable.")
+find_package(KF${QT_VERSION_MAJOR}SyntaxHighlighting REQUIRED)
+if(KF${QT_VERSION_MAJOR}SyntaxHighlighting_VERSION VERSION_LESS "5.39.0")
+    message(WARNING "KSyntaxHighlighting version 5.39.0 or later is required \
+in order to use custom highlighting rules.  KSyntaxHighlighting version \
+${KFSyntaxHighlighting_VERSION} was detected, so these rules will be unavailable.")
     add_definitions("-DKSYN_NO_CUSTOM_RULES_SUPPORT")
 endif()