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

why: Cleaner doctest using built-in ELLIPSIS matching
what:
- Replace 'tag' in mgr.run() pattern with '...tag...' ellipsis

Author: tony

src/libvcs/cmd/git.py

@@ -6033,8 +6033,8 @@ def __init__(
         >>> mgr = GitTagManager(path=example_git_repo.path)
         >>> mgr.create(name='init-doctest-tag', message='For doctest')
         ''
-        >>> 'init-doctest-tag' in mgr.run()
-        True
+        >>> mgr.run()
+        '...init-doctest-tag...'
         """
         #: Directory to check out
         self.path: pathlib.Path