Bump actions/checkout from 5 to 6

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Meson/Ninja
         if: matrix.build_system == 'meson'
@@ -127,7 +127,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Verify tag is on master
         run: |