Remove dependency on pytz

Starting with Python 3.9 a zoneinfo package is available in the standard
library for this feature. There is therefore no need for this dependency
and a compatibility layer is available at
https://pypi.org/project/backports.zoneinfo/ for older Python versions.

agate/data_types/date_time.py

@@ -18,7 +18,7 @@ class DateTime(DataType):
         A formatting string for :meth:`datetime.datetime.strptime` to use
         instead of using regex-based parsing.
     :param timezone:
-        A `pytz <http://pytz.sourceforge.net/>`_ timezone to apply to each
+        A ``ZoneInfo`` timezone to apply to each
         parsed date.
     :param locale:
         A locale specification such as :code:`en_US` or :code:`de_DE` to use

docs/cookbook/datetime.rst

@@ -34,9 +34,13 @@ The second way is to specify a timezone as an argument to the type constructor:
 
 .. code-block:: python
 
-    import pytz
+    try:
+        from zoneinfo import ZoneInfo
+    except ImportError:
+        # Fallback for Python < 3.9
+        from backports.zoneinfo import ZoneInfo
 
-    eastern = pytz.timezone('US/Eastern')
+    eastern = ZoneInfo('US/Eastern')
     datetime_type = agate.DateTime(timezone=eastern)
 
 In this case all timezones that are processed will be set to have the Eastern timezone. Note, the timezone will be **set**, not converted. You cannot use this method to convert your timezones from UTC to another timezone. To do that see :ref:`convert_timezones`.
@@ -60,17 +64,21 @@ If you load data from a spreadsheet in one timezone and you need to convert it t
 
 .. code-block:: python
 
-    import pytz
+    try:
+        from zoneinfo import ZoneInfo
+    except ImportError:
+        # Fallback for Python < 3.9
+        from backports.zoneinfo import ZoneInfo
 
-    us_eastern = pytz.timezone('US/Eastern')
+    us_eastern = ZoneInfo('US/Eastern')
     datetime_type = agate.DateTime(timezone=us_eastern)
 
     column_names = ['what', 'when']
     column_types = [text_type, datetime_type]
 
     table = agate.Table.from_csv('events.csv', columns)
 
-    rome = timezone('Europe/Rome')
+    rome = ZoneInfo('Europe/Rome')
     timezone_shifter = agate.Formula(lambda r: r['when'].astimezone(rome))
 
     table = agate.Table.compute([

setup.py

@@ -54,7 +54,7 @@
             'PyICU>=2.4.2;sys_platform=="linux"',
             'pytest',
             'pytest-cov',
-            'pytz>=2015.4',
+            'backports.zoneinfo;python_version<"3.9"',
         ],
         'docs': [
             'Sphinx>=1.2.2',

tests/test_data_types.py

@@ -6,7 +6,12 @@
 from decimal import Decimal
 
 import parsedatetime
-import pytz
+
+try:
+    from zoneinfo import ZoneInfo
+except ImportError:
+    # Fallback for Python < 3.9
+    from backports.zoneinfo import ZoneInfo
 
 from agate.data_types import Boolean, Date, DateTime, Number, Text, TimeDelta
 from agate.exceptions import CastError
@@ -350,16 +355,16 @@ def test_cast_parser(self):
         ))
 
     def test_cast_parser_timezone(self):
-        tzinfo = pytz.timezone('US/Pacific')
+        tzinfo = ZoneInfo('US/Pacific')
         datetime_type = DateTime(timezone=tzinfo)
 
         values = ('3/1/1994 12:30 PM', '2/17/2011 06:30', None, 'January 5th, 1984 22:37', 'n/a')
         casted = tuple(datetime_type.cast(v) for v in values)
         self.assertSequenceEqual(casted, (
-            tzinfo.localize(datetime.datetime(1994, 3, 1, 12, 30, 0, 0)),
-            tzinfo.localize(datetime.datetime(2011, 2, 17, 6, 30, 0, 0)),
+            datetime.datetime(1994, 3, 1, 12, 30, 0, 0, tzinfo=tzinfo),
+            datetime.datetime(2011, 2, 17, 6, 30, 0, 0, tzinfo=tzinfo),
             None,
-            tzinfo.localize(datetime.datetime(1984, 1, 5, 22, 37, 0, 0)),
+            datetime.datetime(1984, 1, 5, 22, 37, 0, 0, tzinfo=tzinfo),
             None
         ))