cmd/git(docs[GitTagCmd.run]): use ellipsis instead of 'in' check

why: Cleaner doctest using built-in ELLIPSIS matching
what:
- Replace 'tag' in result pattern with '...tag...' ellipsis

Author: tony

src/libvcs/cmd/git.py

@@ -5885,12 +5885,11 @@ def run(
         ...     name='test-tag', message='Test tag'
         ... )
         ''
-        >>> result = GitTagCmd(
+        >>> GitTagCmd(
         ...     path=example_git_repo.path,
         ...     tag_name='test-tag',
         ... ).run()
-        >>> 'test-tag' in result
-        True
+        '...test-tag...'
         """
         local_flags = local_flags if isinstance(local_flags, list) else []
         if command is not None: