ci: add py3.13 to test.yml (theskumar#527)

* ci: add py3.13 to test.yml

* Improve type hints

* fix typo

Author: waketzheng

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
       matrix:
         os:
           - ubuntu-latest
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", pypy3.9, pypy3.10]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", pypy3.9, pypy3.10]
 
     steps:
     - uses: actions/checkout@v4
@@ -21,6 +21,7 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
+        allow-prereleases: true
 
     - name: Upgrade pip
       run: python -m pip install --upgrade pip

src/dotenv/cli.py

@@ -3,7 +3,7 @@
 import shlex
 import sys
 from contextlib import contextmanager
-from typing import Any, Dict, IO, Iterator, List
+from typing import Any, Dict, IO, Iterator, List, Optional
 
 try:
     import click
@@ -16,7 +16,7 @@
 from .version import __version__
 
 
-def enumerate_env():
+def enumerate_env() -> Optional[str]:
     """
     Return a path for the ${pwd}/.env file.