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

2 files changed, 9 insertions, 8 deletions

diff --git a/tests/util/caches/test_deferred_cache.py b/tests/util/caches/test_deferred_cache.py
index ecd9efc4df..c24c33ee91 100644
--- a/tests/util/caches/test_deferred_cache.py
+++ b/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"])
diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py
index cf1e3203a4..afb11b9caf 100644
--- a/tests/util/caches/test_descriptors.py
+++ b/tests/util/caches/test_descriptors.py
@@ -143,8 +143,7 @@ class DescriptorTestCase(unittest.TestCase):
         obj.mock.assert_not_called()
 
     def test_cache_with_sync_exception(self):
-        """If the wrapped function throws synchronously, things should continue to work
-        """
+        """If the wrapped function throws synchronously, things should continue to work"""
 
         class Cls:
             @cached()
@@ -165,8 +164,7 @@ class DescriptorTestCase(unittest.TestCase):
         self.failureResultOf(d, SynapseError)
 
     def test_cache_with_async_exception(self):
-        """The wrapped function returns a failure
-        """
+        """The wrapped function returns a failure"""
 
         class Cls:
             result = None
@@ -282,7 +280,8 @@ class DescriptorTestCase(unittest.TestCase):
                 try:
                     d = obj.fn(1)
                     self.assertEqual(
-                        current_context(), SENTINEL_CONTEXT,
+                        current_context(),
+                        SENTINEL_CONTEXT,
                     )
                     yield d
                     self.fail("No exception thrown")
@@ -374,8 +373,7 @@ class DescriptorTestCase(unittest.TestCase):
         obj.mock.assert_not_called()
 
     def test_cache_iterable_with_sync_exception(self):
-        """If the wrapped function throws synchronously, things should continue to work
-        """
+        """If the wrapped function throws synchronously, things should continue to work"""
 
         class Cls:
             @descriptors.cached(iterable=True)