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/storage/engines/_base.py b/synapse/storage/engines/_base.py
index d6d632dc10..cca839c70f 100644
--- a/synapse/storage/engines/_base.py
+++ b/synapse/storage/engines/_base.py
@@ -94,14 +94,12 @@ class BaseDatabaseEngine(Generic[ConnectionType], metaclass=abc.ABCMeta):
     @property
     @abc.abstractmethod
     def server_version(self) -> str:
-        """Gets a string giving the server version. For example: '3.22.0'
-        """
+        """Gets a string giving the server version. For example: '3.22.0'"""
         ...
 
     @abc.abstractmethod
     def in_transaction(self, conn: Connection) -> bool:
-        """Whether the connection is currently in a transaction.
-        """
+        """Whether the connection is currently in a transaction."""
         ...
 
     @abc.abstractmethod