fix: update GitHub Actions to use latest action versions

- Update docker/login-action from v3 to v4
- Update docker/metadata-action from v5 to v6
- Update docker/build-push-action from v5 to v6

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/deploy.yml

@@ -47,7 +47,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Log in to Container Registry
-      uses: docker/login-action@v3
+      uses: docker/login-action@v4
       with:
         registry: ${{ env.REGISTRY }}
         username: ${{ github.actor }}
@@ -55,7 +55,7 @@ jobs:
 
     - name: Extract metadata
       id: meta
-      uses: docker/metadata-action@v5
+      uses: docker/metadata-action@v6
       with:
         images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
         tags: |
@@ -64,7 +64,7 @@ jobs:
           type=raw,value=latest,enable={{is_default_branch}}
 
     - name: Build and push Docker image
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       with:
         context: .
         push: true