Update black, and run auto formatting over the codebase (#9381)

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

1 files changed, 7 insertions, 3 deletions

diff --git a/synapse/event_auth.py b/synapse/event_auth.py

index 56f8dc9caf..91ad5b3d3c 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -42,7 +42,7 @@ def check(
     do_sig_check: bool = True,
     do_size_check: bool = True,
 ) -> None:
-    """ Checks if this event is correctly authed.
+    """Checks if this event is correctly authed.
 
     Args:
         room_version_obj: the version of the room
@@ -423,7 +423,9 @@ def _can_send_event(event: EventBase, auth_events: StateMap[EventBase]) -> bool:
 
 
 def check_redaction(
-    room_version_obj: RoomVersion, event: EventBase, auth_events: StateMap[EventBase],
+    room_version_obj: RoomVersion,
+    event: EventBase,
+    auth_events: StateMap[EventBase],
 ) -> bool:
     """Check whether the event sender is allowed to redact the target event.
 
@@ -459,7 +461,9 @@ def check_redaction(
 
 
 def _check_power_levels(
-    room_version_obj: RoomVersion, event: EventBase, auth_events: StateMap[EventBase],
+    room_version_obj: RoomVersion,
+    event: EventBase,
+    auth_events: StateMap[EventBase],
 ) -> None:
     user_list = event.content.get("users", {})
     # Validate users