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, 2 deletions

diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index e3d322f2ac..8f68d8dfc8 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -522,7 +522,10 @@ class RegisterRestServlet(RestServlet):
         # not this will raise a user-interactive auth error.
         try:
             auth_result, params, session_id = await self.auth_handler.check_ui_auth(
-                self._registration_flows, request, body, "register a new account",
+                self._registration_flows,
+                request,
+                body,
+                "register a new account",
             )
         except InteractiveAuthIncompleteError as e:
             # The user needs to provide more steps to complete auth.
@@ -665,7 +668,9 @@ class RegisterRestServlet(RestServlet):
             username, as_token
         )
         return await self._create_registration_details(
-            user_id, body, is_appservice_ghost=True,
+            user_id,
+            body,
+            is_appservice_ghost=True,
         )
 
     async def _create_registration_details(