Don't raise "requires a DNS lookup" error on Unix Domain Socket

Don't raise "requires a DNS lookup" error on Unix Domain Socket (#204)
MagicStack · 1st1 · Oct 18, 2018 · 1st1 · Oct 18, 2018 · pax0r
diff --git a/tests/test_udp.py b/tests/test_udp.py
+                f = self.loop.create_datagram_endpoint(
+                    lambda: MyDatagramProto(loop=self.loop), sock=sock)
+            except TypeError as ex:
+                # asyncio in 3.5.0 doesn't have the 'sock' argument