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, 2 insertions, 4 deletions

diff --git a/synapse/federation/persistence.py b/synapse/federation/persistence.py
index 079e2b2fe0..ce5fc758f0 100644
--- a/synapse/federation/persistence.py
+++ b/synapse/federation/persistence.py
@@ -30,8 +30,7 @@ logger = logging.getLogger(__name__)
 
 
 class TransactionActions:
-    """ Defines persistence actions that relate to handling Transactions.
-    """
+    """Defines persistence actions that relate to handling Transactions."""
 
     def __init__(self, datastore):
         self.store = datastore
@@ -57,8 +56,7 @@ class TransactionActions:
     async def set_response(
         self, origin: str, transaction: Transaction, code: int, response: JsonDict
     ) -> None:
-        """Persist how we responded to a transaction.
-        """
+        """Persist how we responded to a transaction."""
         transaction_id = transaction.transaction_id  # type: ignore
         if not transaction_id:
             raise RuntimeError("Cannot persist a transaction with no transaction_id")