fix: Use timezone.utc to be Python 3.9 compatible

Author: winniehell

papermill/engines.py

@@ -122,7 +122,7 @@ def __init__(self, nb, output_path=None, log_output=False, progress_bar=True, au
 
     def now(self):
         """Helper to return current UTC time"""
-        return datetime.datetime.now(datetime.UTC)
+        return datetime.datetime.now(datetime.timezone.utc)
 
     def set_timer(self):
         """

papermill/parameterize.py

@@ -1,4 +1,4 @@
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from uuid import uuid4
 
 import nbformat
@@ -23,7 +23,7 @@ def add_builtin_parameters(parameters):
         "pm": {
             "run_uuid": str(uuid4()),
             "current_datetime_local": datetime.now(),
-            "current_datetime_utc": datetime.now(UTC),
+            "current_datetime_utc": datetime.now(timezone.utc),
         }
     }