Replace pytz dependency with zoneinfo. Fix #2958 (#3161)

pelican/utils.py

@@ -18,10 +18,12 @@ from operator import attrgetter
 
 import dateutil.parser
 
+try:
+    import zoneinfo
+except ModuleNotFoundError:
+    from backports import zoneinfo
 from markupsafe import Markup
 
-import pytz
-
 
 logger = logging.getLogger(__name__)
 
@@ -919,10 +921,11 @@ class FileSystemWatcher:
 def set_date_tzinfo(d, tz_name=None):
     """Set the timezone for dates that don't have tzinfo"""
     if tz_name and not d.tzinfo:
-        tz = pytz.timezone(tz_name)
-        d = tz.localize(d)
-        return SafeDatetime(d.year, d.month, d.day, d.hour, d.minute, d.second,
-                            d.microsecond, d.tzinfo)
+        timezone = zoneinfo.ZoneInfo(tz_name)
+        d = d.replace(tzinfo=timezone)
+        return SafeDatetime(
+            d.year, d.month, d.day, d.hour, d.minute, d.second, d.microsecond, d.tzinfo
+        )
     return d