standardize packaging, tooling, docs, CI, and licensing

mail_intake/credentials/redis.py

@@ -24,8 +24,8 @@ Credential validation, refresh, rotation, and acquisition remain the
 responsibility of authentication provider implementations.
 """
 
-
-from typing import Optional, TypeVar, Callable
+from collections.abc import Callable
+from typing import TypeVar
 
 from mail_intake.credentials.store import CredentialStore
 
@@ -61,7 +61,7 @@ class RedisCredentialStore(CredentialStore[T]):
         key: str,
         serialize: Callable[[T], bytes],
         deserialize: Callable[[bytes], T],
-        ttl_seconds: Optional[int] = None,
+        ttl_seconds: int | None = None,
     ):
         """
         Initialize a Redis-backed credential store.
@@ -88,7 +88,7 @@ class RedisCredentialStore(CredentialStore[T]):
         self.deserialize = deserialize
         self.ttl_seconds = ttl_seconds
 
-    def load(self) -> Optional[T]:
+    def load(self) -> T | None:
         """
         Load credentials from Redis.