lint: ruff format + one auto-fix so the push self-test is green again

`scripts/lint.sh --fix` from the pinned lint devshell: 90 Python files
reformatted (ruff format, mechanical) and one C420 (dict comprehension →
dict.fromkeys) in tests/unit/test_f211_sso_skip.py. The push self-test had
been failing at the lint stage since build 1313 (2026-08-31) on exactly
these files; nothing else changed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FqkQq3CDmFWcQ7u1LzoyRz

tests/matrix-synapse/test_install.py

@@ -26,6 +26,6 @@ def test_serving_and_client_api(live_app, meta):
     # The client-API version document is real synapse JSON (proves the app, not just a proxy 200).
     body = lifecycle.http_body(live_app, "/_matrix/client/versions")
     doc = json.loads(body)
-    assert (
-        isinstance(doc.get("versions"), list) and doc["versions"]
-    ), "no matrix client versions advertised"
+    assert isinstance(doc.get("versions"), list) and doc["versions"], (
+        "no matrix client versions advertised"
+    )