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, 5 insertions, 5 deletions

diff --git a/synapse/replication/tcp/external_cache.py b/synapse/replication/tcp/external_cache.py
index 34fa3ff5b3..d89a36f25a 100644
--- a/synapse/replication/tcp/external_cache.py
+++ b/synapse/replication/tcp/external_cache.py
@@ -60,8 +60,7 @@ class ExternalCache:
         return self._redis_connection is not None
 
     async def set(self, cache_name: str, key: str, value: Any, expiry_ms: int) -> None:
-        """Add the key/value to the named cache, with the expiry time given.
-        """
+        """Add the key/value to the named cache, with the expiry time given."""
 
         if self._redis_connection is None:
             return
@@ -76,13 +75,14 @@ class ExternalCache:
 
         return await make_deferred_yieldable(
             self._redis_connection.set(
-                self._get_redis_key(cache_name, key), encoded_value, pexpire=expiry_ms,
+                self._get_redis_key(cache_name, key),
+                encoded_value,
+                pexpire=expiry_ms,
             )
         )
 
     async def get(self, cache_name: str, key: str) -> Optional[Any]:
-        """Look up a key/value in the named cache.
-        """
+        """Look up a key/value in the named cache."""
 
         if self._redis_connection is None:
             return None