fix(tests): silence Windows mypy on os.fork / socket.AF_UNIX

The fork-safety and Unix-socket tests are guarded by
@pytest.mark.skipif(sys.platform == "win32"), but mypy still type-checks
the bodies on Windows where neither attribute exists.  Match the
existing conftest pattern with `type: ignore[attr-defined, unused-ignore]`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: rustyconover

tests/test_transport_kind.py

@@ -366,7 +366,7 @@ def test_fork_after_make_wsgi_app(self) -> None:
 
         # Use a pipe to confirm the child fired the hook in its own process.
         r_fd, w_fd = os.pipe()
-        pid = os.fork()
+        pid = os.fork()  # type: ignore[attr-defined, unused-ignore]
         if pid == 0:
             # Child
             os.close(r_fd)
@@ -429,7 +429,7 @@ class TestUnixTransportRaw:
 
     def test_isinstance_dispatch(self) -> None:
         """A bare UnixTransport bound via serve() reports UNIX."""
-        s1, s2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+        s1, s2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)  # type: ignore[attr-defined, unused-ignore]
         client_transport = UnixTransport(s1)
         server_transport = UnixTransport(s2)
         impl = _RecordingImpl()