feat(python): fixed typing

flipt-python/flipt/authentication/__init__.py

@@ -1,19 +1,19 @@
 class AuthenticationStrategy:
-    def authenticate(self, headers: dict):
+    def authenticate(self, headers: dict[str, str]) -> None:
         raise NotImplementedError()
 
 
 class ClientTokenAuthentication(AuthenticationStrategy):
-    def __init__(self, token: str):
+    def __init__(self, token: str) -> None:
         self.token = token
 
-    def authenticate(self, headers: dict):
+    def authenticate(self, headers: dict[str, str]) -> None:
         headers["Authorization"] = f"Bearer {self.token}"
 
 
 class JWTAuthentication(AuthenticationStrategy):
-    def __init__(self, token: str):
+    def __init__(self, token: str) -> None:
         self.token = token
 
-    def authenticate(self, headers: dict):
+    def authenticate(self, headers: dict[str, str]) -> None:
         headers["Authorization"] = f"JWT {self.token}"