add backports.zoneinfo to ci deps

ci/deps/actions-38-downstream_compat.yaml

@@ -19,6 +19,7 @@ dependencies:
   - python-dateutil
   - numpy
   - pytz
+  - backports.zoneinfo
 
   # optional dependencies
   - beautifulsoup4

ci/deps/actions-38-minimum_versions.yaml

@@ -20,6 +20,7 @@ dependencies:
   - python-dateutil=2.8.1
   - numpy=1.18.5
   - pytz=2020.1
+  - backports.zoneinfo
 
   # optional dependencies, markupsafe for jinja2
   - beautifulsoup4=4.8.2

pandas/conftest.py

@@ -1167,6 +1167,7 @@ def iris(datapath):
     timezone(timedelta(hours=1)),
     timezone(timedelta(hours=-1), name="foo"),
     zoneinfo.ZoneInfo("US/Pacific"),
+    zoneinfo.ZoneInfo("UTC"),
 ]
 TIMEZONE_IDS = [repr(i) for i in TIMEZONES]
 
@@ -1193,7 +1194,9 @@ def tz_aware_fixture(request):
 tz_aware_fixture2 = tz_aware_fixture
 
 
-@pytest.fixture(params=["utc", "dateutil/UTC", utc, tzutc(), timezone.utc])
+@pytest.fixture(
+    params=["utc", "dateutil/UTC", utc, tzutc(), timezone.utc, zoneinfo.ZoneInfo("UTC")]
+)
 def utc_fixture(request):
     """
     Fixture to provide variants of UTC timezone strings and tzinfo objects.