Use backports.zoneinfo in job_metrics package under Python <3.9

Fix import errors in test_galaxy_packages_for_pulsar tests.

lib/galaxy/job_metrics/instrumenters/core.py

@@ -3,7 +3,6 @@
 import datetime
 import json
 import logging
-import zoneinfo
 from typing import (
     Any,
     Dict,
@@ -19,6 +18,12 @@ from ..formatting import (
 )
 from ..safety import Safety
 
+try:
+    import zoneinfo
+except ImportError:
+    # Python < 3.9
+    from backports import zoneinfo  # type: ignore[no-redef]
+
 log = logging.getLogger(__name__)
 
 GALAXY_SLOTS_KEY = "galaxy_slots"

packages/job_metrics/setup.cfg

@@ -35,6 +35,7 @@ version = 25.0.dev0
 include_package_data = True
 install_requires =
     galaxy-util
+    backports.zoneinfo;python_version<'3.9'
 packages = find:
 python_requires = >=3.7