Update https://gitea.com/actions/checkout action to v6

Reviewed-on: #21

.gitea/workflows/build_container.yaml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - uses: https://gitea.com/actions/checkout@v4
+    - uses: https://gitea.com/actions/checkout@v6
 
     - name: Fetch tags from main branch
       id: version
@@ -42,7 +42,7 @@ jobs:
       uses: docker/setup-buildx-action@v3
 
     - name: Build and push
-      uses: docker/build-push-action@v6
+      uses: docker/build-push-action@v5
       with:
         context: .
         # use the current commit SHA as the tag