test(p2p/discv5): fix test on go 1.14 ethereum#20724 (#2407)

Author: gzliudan

p2p/discv5/node_test.go

@@ -141,7 +141,7 @@ var parseNodeTests = []struct {
 	{
 		// This test checks that errors from url.Parse are handled.
 		rawurl:    "://foo",
-		wantError: `parse "://foo": missing protocol scheme`,
+		wantError: `missing protocol scheme`,
 	},
 }