chore(deps): Bump docker/metadata-action to v5 (#562)

Bump the docker/metadata-action in our metadata action to v5.

We should refactor this repo's CI to be more like the cluster api
provider packet CI. There is no reason to use this custom composite
metadata action anymore.

.github/actions/metadata/action.yaml

@@ -39,7 +39,7 @@ runs:
       echo "images=${IMAGES}" >> $GITHUB_OUTPUT
   - name: Docker manager metadata
     id: meta
-    uses: docker/metadata-action@v4
+    uses: docker/metadata-action@v5
     with:
       images: ${{ steps.image-urls.outputs.images }}
       flavor: ${{ inputs.metadata_flavor }}