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/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 89f0b38535..e676c2cac4 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -149,8 +149,7 @@ KNOWN_KEYS = {
 
 
 def intern_string(string):
-    """Takes a (potentially) unicode string and interns it if it's ascii
-    """
+    """Takes a (potentially) unicode string and interns it if it's ascii"""
     if string is None:
         return None
 
@@ -161,8 +160,7 @@ def intern_string(string):
 
 
 def intern_dict(dictionary):
-    """Takes a dictionary and interns well known keys and their values
-    """
+    """Takes a dictionary and interns well known keys and their values"""
     return {
         KNOWN_KEYS.get(key, key): _intern_known_values(key, value)
         for key, value in dictionary.items()