Unisender Go: Fix integration tests (not support merge_metadata, fix …

…datetime format)

tests/test_unisender_go_integration.py

@@ -75,7 +75,8 @@ def test_simple_send(self):
         self.assertEqual(anymail_status.message_id, message_id)
 
     def test_all_options(self):
-        send_at = datetime.now() + timedelta(minutes=2)
+        send_at_datetime = datetime.now() + timedelta(minutes=2)
+        send_at = send_at_datetime.strftime("%Y-%m-%d %H:%M:%S")
         message = AnymailMessage(
             subject="Anymail Unisender Go all-options integration test",
             body="This is the text body",
@@ -141,10 +142,6 @@ def test_template(self):
             },
             merge_global_data={"ship_date": "yesterday"},
             metadata={"customer-id": "unknown", "meta2": 2},
-            merge_metadata={
-                "[email protected]": {"customer-id": "ZXK9123"},
-                "[email protected]": {"customer-id": "ZZT4192"},
-            },
         )
         message.from_email = None  # use template sender
         message.attach("attachment1.txt", "Here is some\ntext", "text/plain")