Fix some incorrect/incomplete annotations for redis.client.PubSub (#3408)

* redis: Fix return value declarations in redis.client.PubSub

get_message() was declared incorrectly. Start here:

  https://github.com/andymccurdy/redis-py/blob/3.3.11/redis/client.py#L3298-L3300

where it's obvious that get_message() returns either None or the
output of handle_message().

So what does handle_message() return? Combine:

  https://github.com/andymccurdy/redis-py/blob/3.3.11/redis/client.py#L3316-L3336
  https://github.com/andymccurdy/redis-py/blob/3.3.11/redis/client.py#L3366

and you can see it returns None or a dict mapping str to something.

* redis: Fix incorrect declaration for PubSub.get_message() argument

Docstrings says it's a float:

  https://github.com/andymccurdy/redis-py/blob/3.3.11/redis/client.py#L3293-L3295

And it eventually gets passed to settimeout() on a socket:

  https://github.com/andymccurdy/redis-py/blob/3.3.11/redis/connection.py#L182

* redis: Annotate one more method arg in PubSub class

get_message() and handle_message() are closely related:
ignore_subscribe_message does the same in both, and its default value
in both is False.

third_party/2and3/redis/client.pyi

@@ -1,5 +1,5 @@
 from datetime import timedelta
-from typing import Any, Iterable, Text, Optional, Mapping, Tuple, Union, Callable, List
+from typing import Any, Iterable, Text, Optional, Mapping, Tuple, Union, Callable, List, Dict
 
 from .connection import ConnectionPool
 
@@ -307,8 +307,8 @@ class PubSub:
     def subscribe(self, *args: Text, **kwargs: Callable[[Any], None]) -> None: ...
     def unsubscribe(self, *args: Text) -> None: ...
     def listen(self): ...
-    def get_message(self, ignore_subscribe_messages: bool = ..., timeout: int = ...) -> Optional[bytes]: ...
-    def handle_message(self, response, ignore_subscribe_messages=...): ...
+    def get_message(self, ignore_subscribe_messages: bool = ..., timeout: float = ...) -> Optional[Dict[str, Any]]: ...
+    def handle_message(self, response, ignore_subscribe_messages: bool = ...) -> Optional[Dict[str, Any]]: ...
     def run_in_thread(self, sleep_time=...): ...
 
 class BasePipeline: