fixed up ping_timeout

Author: kevin-tritz

adafruit_minimqtt/adafruit_minimqtt.py

@@ -574,8 +574,8 @@ def ping(self) -> list[int]:
             rc = self._wait_for_msg()
             if rc:
                 rcs.append(rc)
-            if ticks_diff(ticks_ms(), stamp) > ping_timeout * 1000:
-                raise MMQTTException("PINGRESP not returned from broker.")
+            if ticks_diff(ticks_ms(), stamp) / 1000 > ping_timeout:
+                raise MMQTTException(f"PINGRESP not returned from broker within {ping_timeout} seconds.")
         return rcs
 
     # pylint: disable=too-many-branches, too-many-statements