Improve pure time precision

Signed-off-by: Ashwini Kumar Pandey <ashwini165@gmail.com>

Author: ashwini-k-pandey

python/fledge/tasks/purge/purge.py

@@ -29,8 +29,8 @@
     All these statistics are inserted into the log table
 """
 import time
-import pytz
-from datetime import datetime, timedelta
+
+from datetime import datetime, timedelta, timezone
 
 from fledge.common import statistics
 from fledge.common.audit_logger import AuditLogger
@@ -134,8 +134,8 @@ async def purge_data(self, config):
         unsent_retained = 0
         duration = 0
         method = None
-        timezone = pytz.timezone('UTC')  # You can replace 'UTC' with your desired timezone
-        start_time = datetime.now(timezone).strftime('%Y-%m-%d %H:%M:%S.%f %Z%z')
+
+        start_time = datetime.now(timezone.utc).isoformat(' ')
 
         if config['retainUnsent']['value'].lower() == "purge unsent":
             flag = "purge"
@@ -241,7 +241,7 @@ async def purge_data(self, config):
             # skip logging as its already done in details for this operation in case of error
             # FIXME: check if ex.error jdoc has retryable True then retry the operation else move on
             pass
-        end_time = datetime.now(timezone).strftime('%Y-%m-%d %H:%M:%S.%f %Z%z')
+        end_time = datetime.now(timezone.utc).isoformat(' ')
 
         if total_rows_removed > 0:
             """ Only write an audit log entry when rows are removed """