remove test_loop dependence on mqtt.get_monotonic_time function

Author: kevin-tritz

tests/test_loop.py

@@ -142,7 +142,8 @@ def test_loop_basic(self) -> None:
             time_before = time.monotonic()
             timeout = random.randint(3, 8)
             # pylint: disable=protected-access
-            mqtt_client._last_msg_sent_timestamp = mqtt_client.get_monotonic_time()
+            # mqtt_client._last_msg_sent_timestamp = mqtt_client.get_monotonic_time()
+            mqtt_client._last_msg_sent_timestamp = time.monotonic()
             rcs = mqtt_client.loop(timeout=timeout)
             time_after = time.monotonic()