Remove commented-out is_config_level function

And the commented-out imports that had been solely to support it.

Author: EliahKagan

git/types.py

@@ -33,11 +33,6 @@
         runtime_checkable,
     )
 
-# if sys.version_info >= (3, 10):
-#     from typing import TypeGuard  # noqa: F401
-# else:
-#     from typing_extensions import TypeGuard  # noqa: F401
-
 if TYPE_CHECKING:
     from git.repo import Repo
     from git.objects import Commit, Tree, TagObject, Blob
@@ -117,10 +112,6 @@
 ConfigLevels_Tup = Tuple[Literal["system"], Literal["user"], Literal["global"], Literal["repository"]]
 """Static type of a tuple of the four strings representing configuration levels."""
 
-# def is_config_level(inp: str) -> TypeGuard[Lit_config_levels]:
-#     # return inp in get_args(Lit_config_level)  # only py >= 3.8
-#     return inp in ("system", "user", "global", "repository")
-
 # Progress parameter type alias -----------------------------------------
 
 CallableProgress = Optional[Callable[[int, Union[str, float], Union[str, float, None], str], None]]