* fixed discover_repository type annotation it return None incase no repository was found

* removed unused import of submodule type

Author: OrHayat

pygit2/_pygit2.pyi

@@ -1,6 +1,6 @@
 from typing import Iterator, Literal, Optional, overload
 from io import IOBase
-from . import Index, Submodule
+from . import Index
 from .enums import (
     ApplyLocation,
     BranchType,
@@ -558,7 +558,7 @@ class Worktree:
 
 def discover_repository(
     path: str, across_fs: bool = False, ceiling_dirs: str = ...
-) -> str: ...
+) -> str | None: ...
 def hash(data: bytes) -> Oid: ...
 def hashfile(path: str) -> Oid: ...
 def init_file_backend(path: str, flags: int = 0) -> object: ...