Fix mypy: proxies type must be Mapping, not MutableMapping

requests' HTTPAdapter.send declares proxies as Mapping[str, str] | None
(via types-requests). Overriding with the more specific MutableMapping
is an invalid override under mypy 1.18 strict mode.

Signed-off-by: rahulsmahadev <rahul.mahadev@databricks.com>

Author: rahulsmahadev

pyiceberg/catalog/rest/__init__.py

@@ -17,7 +17,7 @@
 from __future__ import annotations
 
 from collections import deque
-from collections.abc import MutableMapping
+from collections.abc import Mapping
 from enum import Enum
 from typing import (
     TYPE_CHECKING,
@@ -425,7 +425,7 @@ def send(
         timeout: None | float | tuple[float, float] | tuple[float, None] = None,
         verify: bool | str = True,
         cert: None | bytes | str | tuple[bytes | str, bytes | str] = None,
-        proxies: MutableMapping[str, str] | None = None,
+        proxies: Mapping[str, str] | None = None,
     ) -> Response:
         if timeout is None:
             timeout = self._timeout