GitHub workflows: bump actions to their latest versions (#190)

Co-authored-by: Andreas Deininger <[email protected]>

Author: deining

.github/workflows/docker.yml

@@ -14,7 +14,7 @@ jobs:
   docker:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Log in to the Container registry
         uses: docker/login-action@v3

.github/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
             os: windows-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions/cache@v4
         if: runner.os != 'macOS'
         with: