Bump actions/checkout from 5 to 6 (#25)

Author: dependabot[bot]

.github/workflows/qt5_6.yml

@@ -44,7 +44,7 @@ jobs:
 
     steps:
       - name: 👀 Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: ✅ Determine current Repository
         if: ${{ !startsWith(github.repository, env.REPOSITORY) }}