GitHub Action CI: Add Go source file format check (#6090)

https://github.com/XTLS/Xray-core/pull/6057#issuecomment-4364819830

And https://github.com/XTLS/Xray-core/pull/6149#issuecomment-4546876261

transport/internet/tls/ech_test.go

@@ -44,7 +44,6 @@ func TestECHDial(t *testing.T) {
 	echConfigCache, ok := GlobalECHConfigCache.Load(ECHCacheKey("udp://1.1.1.1", "encryptedsni.com", nil))
 	if !ok {
 		t.Error("ECH config cache not found")
-
 	}
 	ok = echConfigCache.UpdateLock.TryLock()
 	if !ok {