Add suitable "GitFetch" for friendica

library/friendica

@@ -2,6 +2,7 @@
 
 Maintainers: Friendica <[email protected]> (@friendica), Philipp Holzer <[email protected]> (@nupplaphil)
 GitRepo: https://github.com/friendica/docker.git
+GitFetch: refs/heads/stable
 
 Tags: 2021.09-apache, apache, stable-apache, 2021.09, latest, stable
 Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, ppc64le, s390x