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/replication/http/register.py b/synapse/replication/http/register.py

index 7b12ec9060..d005f38767 100644
--- a/synapse/replication/http/register.py
+++ b/synapse/replication/http/register.py
@@ -22,8 +22,7 @@ logger = logging.getLogger(__name__)
 
 
 class ReplicationRegisterServlet(ReplicationEndpoint):
-    """Register a new user
-    """
+    """Register a new user"""
 
     NAME = "register_user"
     PATH_ARGS = ("user_id",)
@@ -97,8 +96,7 @@ class ReplicationRegisterServlet(ReplicationEndpoint):
 
 
 class ReplicationPostRegisterActionsServlet(ReplicationEndpoint):
-    """Run any post registration actions
-    """
+    """Run any post registration actions"""
 
     NAME = "post_register"
     PATH_ARGS = ("user_id",)