Remove pytz and replace usage with core python modules (#80)

Pytz is deprecated since Python 3.9. You might want to keep it for backwards
compatibility for Python 3.8. However, turning naive datetimes into UTC timezone
datetimes seems also possible in Python 3.8 without using the pytc library.

Author: MerijnBol

.pre-commit-config.yaml

@@ -5,7 +5,7 @@ repos:
       - id: mypy
         args: [--strict]
         additional_dependencies:
-          [pydantic, pytest, pytest_mock, types-requests, flagsmith-flag-engine, responses, types-pytz, sseclient-py]
+          [pydantic, pytest, pytest_mock, types-requests, flagsmith-flag-engine, responses, sseclient-py]
   - repo: https://github.com/PyCQA/isort
     rev: 5.12.0
     hooks:

flagsmith/flagsmith.py

@@ -1,9 +1,8 @@
 import json
 import logging
 import typing
-from datetime import datetime
+from datetime import datetime, timezone
 
-import pytz
 import requests
 from flag_engine import engine
 from flag_engine.environments.models import EnvironmentModel
@@ -212,15 +211,15 @@ def handle_stream_event(self, event: StreamEvent) -> None:
             ) from e
 
         if stream_updated_at.tzinfo is None:
-            stream_updated_at = pytz.utc.localize(stream_updated_at)
+            stream_updated_at = stream_updated_at.astimezone(timezone.utc)
 
         if not self._environment:
             raise ValueError(
                 "Unable to access environment. Environment should not be null"
             )
         environment_updated_at = self._environment.updated_at
         if environment_updated_at.tzinfo is None:
-            environment_updated_at = pytz.utc.localize(environment_updated_at)
+            environment_updated_at = environment_updated_at.astimezone(timezone.utc)
 
         if stream_updated_at > environment_updated_at:
             self.update_environment()

poetry.lock

@@ -15,7 +15,6 @@ requests = "^2.27.1"
 requests-futures = "^1.0.0"
 flagsmith-flag-engine = "^5.1.0"
 sseclient-py = "^1.8.0"
-pytz = "^2023.4"
 
 [tool.poetry.group.dev]
 optional = true
@@ -31,7 +30,6 @@ isort = "^5.12.0"
 mypy = "^1.7.1"
 types-requests = "^2.31.0.10"
 pytest-cov = "^4.1.0"
-types-pytz = "^2024.1.0.20240203"
 
 [tool.mypy]
 plugins = ["pydantic.mypy"]