fix: add missing import for math library

src/monitoring/service/MetricsDBTools.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import time
+import math
 from random import random
 
 from questdb.ingress import Sender, IngressError
@@ -326,4 +327,4 @@ class MetricsDB():
             else:
                 LOGGER.debug(f"No new data for the alarm of KPI {kpi_id}")
         except (Exception) as e:
-            LOGGER.debug(f"Alarm data cannot be retrieved. {e}")
\ No newline at end of file
+            LOGGER.debug(f"Alarm data cannot be retrieved. {e}")