Merge pull request #2222 from fkrull/patch-v2020.7

lib: add missing GI annotation

src/libostree/ostree-repo-static-delta-core.c

@@ -1076,7 +1076,7 @@ _ostree_repo_static_delta_dump (OstreeRepo                    *self,
  * @self: Repo
  * @delta_id: delta path
  * @sign: Signature engine used to check superblock
- * @out_success_message: success message
+ * @out_success_message: (out) (nullable) (optional): success message
  * @error: Error
  *
  * Verify static delta file signature.