Fix mypy 1.16.0 type hint errors

.pre-commit-config.yaml

@@ -28,7 +28,7 @@ repos:
       args: [--fix, --exit-non-zero-on-fix]
 
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: v1.15.0
+  rev: v1.16.0
   hooks:
   - id: mypy
     exclude: tests/data

src/pip/_internal/network/auth.py

@@ -230,7 +230,7 @@ def __init__(
     ) -> None:
         self.prompting = prompting
         self.index_urls = index_urls
-        self.keyring_provider = keyring_provider  # type: ignore[assignment]
+        self.keyring_provider = keyring_provider
         self.passwords: dict[str, AuthInfo] = {}
         # When the user is prompted to enter credentials and keyring is
         # available, we will offer to save them. If the user accepts,

tests/lib/venv.py

@@ -226,7 +226,7 @@ def sitecustomize(self) -> str | None:
         return self._sitecustomize
 
     @sitecustomize.setter
-    def sitecustomize(self, value: str) -> None:
+    def sitecustomize(self, value: str | None) -> None:
         self._sitecustomize = value
         self._customize_site()