chore: Drop dependency on pytz by using stdlib `datetime.timezone.u…

…tc` (#721)

* Fix type hints for non-None return

* Use stdlib instead of pytz.utc

---------

Co-authored-by: Athira Sabu <102021496+AsabuHere@users.noreply.github.com>

requirements.txt

@@ -1,5 +1,4 @@
 pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability
-pytz
 requests>=2.0.0
 PyJWT>=2.0.0, <3.0.0
 aiohttp>=3.8.4

setup.py

@@ -21,7 +21,6 @@
     keywords=["twilio", "twiml"],
     python_requires=">=3.7.0",
     install_requires=[
-        "pytz",
         "requests >= 2.0.0",
         "PyJWT >= 2.0.0, < 3.0.0",
         "aiohttp>=3.8.4",

tests/unit/base/test_deserialize.py

@@ -2,8 +2,6 @@
 import unittest
 from decimal import Decimal
 
-import pytz
-
 from twilio.base import deserialize
 
 
@@ -21,7 +19,7 @@ def test_not_parsable(self):
 class Iso8601DateTimeTestCase(unittest.TestCase):
     def test_parsable(self):
         actual = deserialize.iso8601_datetime("2015-01-02T03:04:05Z")
-        expected = datetime.datetime(2015, 1, 2, 3, 4, 5, 0, pytz.utc)
+        expected = datetime.datetime(2015, 1, 2, 3, 4, 5, 0, datetime.timezone.utc)
         self.assertEqual(expected, actual)
 
     def test_not_parsable(self):

twilio/base/deserialize.py

@@ -3,13 +3,11 @@
 from email.utils import parsedate
 from typing import Optional, Union
 
-import pytz
-
 ISO8601_DATE_FORMAT = "%Y-%m-%d"
 ISO8601_DATETIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
 
 
-def iso8601_date(s: str) -> Optional[Union[datetime.date, str]]:
+def iso8601_date(s: str) -> Union[datetime.date, str]:
     """
     Parses an ISO 8601 date string and returns a UTC date object or the string
     if the parsing failed.
@@ -19,7 +17,7 @@ def iso8601_date(s: str) -> Optional[Union[datetime.date, str]]:
     try:
         return (
             datetime.datetime.strptime(s, ISO8601_DATE_FORMAT)
-            .replace(tzinfo=pytz.utc)
+            .replace(tzinfo=datetime.timezone.utc)
             .date()
         )
     except (TypeError, ValueError):
@@ -28,15 +26,15 @@ def iso8601_date(s: str) -> Optional[Union[datetime.date, str]]:
 
 def iso8601_datetime(
     s: str,
-) -> Optional[Union[datetime.datetime, str]]:
+) -> Union[datetime.datetime, str]:
     """
     Parses an ISO 8601 datetime string and returns a UTC datetime object,
     or the string if parsing failed.
     :param s: ISO 8601-formatted datetime string (2015-01-25T12:34:56Z)
     """
     try:
         return datetime.datetime.strptime(s, ISO8601_DATETIME_FORMAT).replace(
-            tzinfo=pytz.utc
+            tzinfo=datetime.timezone.utc
         )
     except (TypeError, ValueError):
         return s
@@ -52,10 +50,10 @@ def rfc2822_datetime(s: str) -> Optional[datetime.datetime]:
     date_tuple = parsedate(s)
     if date_tuple is None:
         return None
-    return datetime.datetime(*date_tuple[:6]).replace(tzinfo=pytz.utc)
+    return datetime.datetime(*date_tuple[:6]).replace(tzinfo=datetime.timezone.utc)
 
 
-def decimal(d: Optional[str]) -> Optional[Union[Decimal, str]]:
+def decimal(d: Optional[str]) -> Union[Decimal, str]:
     """
     Parses a decimal string into a Decimal
     :param d: decimal string
@@ -65,7 +63,7 @@ def decimal(d: Optional[str]) -> Optional[Union[Decimal, str]]:
     return Decimal(d, BasicContext)
 
 
-def integer(i: str) -> Optional[Union[int, str]]:
+def integer(i: str) -> Union[int, str]:
     """
     Parses an integer string into an int
     :param i: integer string