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
`](80d6dc9783/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

tests/util/caches/test_deferred_cache.py

@@ -232,7 +232,10 @@ class DeferredCacheTestCase(TestCase):
 
     def test_eviction_iterable(self):
         cache = DeferredCache(
-            "test", max_entries=3, apply_cache_factor_from_config=False, iterable=True,
+            "test",
+            max_entries=3,
+            apply_cache_factor_from_config=False,
+            iterable=True,
         )
 
         cache.prefill(1, ["one", "two"])