Explicitly fetch tags from googlesource remote.

The default fetch remote is a local directory, so explicitly fetch tags from the true upstream.

Change-Id: Id5d25073a758d7cee220ac2dd6c82c7bb612e061
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/4664
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Reviewed-by: Nurhan Turgut <nurhan@google.com>