hack/actions: fix release image tag fetching (projectcontour#4311)

Adds `--force` to `git fetch --tags` to
work with the v2 checkout action.

Closes projectcontour#4309.

Signed-off-by: Steve Kriss <krisss@vmware.com>

hack/actions/build-and-push-release-images.sh

@@ -28,7 +28,7 @@ fi
 
 # Fetch all tags so we can check if the current tag
 # is the highest semver.
-git fetch --tags
+git fetch --tags --force
 
 HIGHEST_SEMVER_TAG=""