GitHub Actions: Updated to Qt 6.6.1

This might eventually help people on Wayland to have working dock
widgets.

Issue #3412

.github/workflows/packages.yml

@@ -48,7 +48,7 @@ jobs:
         include:
         - qt_version: 5.15.2
           qt_version_major: 5
-        - qt_version: 6.5.3
+        - qt_version: 6.6.1
           qt_version_major: 6
 
     env:
@@ -192,7 +192,7 @@ jobs:
         - qt_version: 5.12.12
           version_suffix: "10.12-10.15"
           architectures: x86_64
-        - qt_version: 6.5.3
+        - qt_version: 6.6.1
           version_suffix: "11+"
           architectures: x86_64,arm64
 
@@ -284,7 +284,7 @@ jobs:
           mingw_version: 8.1.0
           mingw_component: mingw
           mingw_path: /c/Qt/Tools/mingw810_32/bin
-        - qt_version: 6.5.3
+        - qt_version: 6.6.1
           qt_version_major: 6
           qt_toolchain: win64_mingw
           arch: 64