Add `typing-extensions` to dependencies

[jlondonobo]

What's the issue?

fastexcel uses typing_extensions: https://github.com/ToucanToco/fastexcel/blob/81690535b05b14b5953c21c9e7fb77dfd915dcda/python/fastexcel/__init__.py#L5

However, typing_extensions is not part of dependencies in pyproject.toml

This causes a ModuleNotFoundError when fastexcel is installed by itself.

How to reproduce the bug?

1. Create a virtual environment:

   python -m venv .venv/
   source .venv/bin/activate

2. Install fastexcel:

   pip install -e .
   python

3. Import fastexcel

   import fastexcel

Error message

Python 3.12.2 (main, Feb 20 2024, 04:06:49) [Clang 14.0.0 (clang-1400.0.29.202)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import fastexcel
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/joselondono/Documents/forks/fastexcel/python/fastexcel/__init__.py", line 5, in <module>
    from typing_extensions import TypeAlias
ModuleNotFoundError: No module named 'typing_extensions'

[PrettyWood]

Hello @jlondonobo Thank you for the great report! You're absolutely right.

[PrettyWood]

closed by #227