ci(docker): upgrade login-action v3 to v4

v3 uses Node.js 20 which is deprecated by GitHub Actions.
v4 supports Node.js 24.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: theothersideofgod

.github/workflows/docker.yaml

@@ -73,7 +73,7 @@ jobs:
 
       - name: Log in to GHCR
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}