cmd/git(fix[GitRemoteManager]): Fix invalid doctest using quiet parameter

why: The doctest used quiet=True, but git remote has no --quiet flag.
With kwargs passthrough now working, this caused a TypeError.
what:
- Replace quiet=True with check_returncode=False in doctest

Author: tony

src/libvcs/cmd/git.py

@@ -4179,7 +4179,7 @@ def __init__(
         >>> GitRemoteManager(path=tmp_path)
         <GitRemoteManager path=...>
 
-        >>> GitRemoteManager(path=tmp_path).run(quiet=True)
+        >>> GitRemoteManager(path=tmp_path).run(check_returncode=False)
         'fatal: not a git repository (or any of the parent directories): .git'
 
         >>> GitRemoteManager(