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/custom/test_federation_version.py

@@ -34,12 +34,12 @@ def test_federation_version_endpoint(live_app):
     assert status == 200, f"GET {url} HTTP {status} (expected 200)"
     assert isinstance(body, dict), f"federation version returned non-dict: {type(body).__name__}"
     server = body.get("server")
-    assert isinstance(
-        server, dict
-    ), f"federation version response missing 'server' envelope: {body!r}"
+    assert isinstance(server, dict), (
+        f"federation version response missing 'server' envelope: {body!r}"
+    )
     name = server.get("name")
     assert name == "Synapse", f"server.name={name!r}, expected 'Synapse'"
     version = server.get("version")
-    assert (
-        isinstance(version, str) and len(version) > 0
-    ), f"server.version is not a non-empty string: {version!r}"
+    assert isinstance(version, str) and len(version) > 0, (
+        f"server.version is not a non-empty string: {version!r}"
+    )