Minimal version requirements for typing_extensions missing

[observingClouds]

What I have done

When importing ipldstore on python3.9 (and probably below), I get the following error:

Python 3.9.7 | packaged by conda-forge | (default, Sep 29 2021, 20:33:18) 
[Clang 11.1.0 ] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ipldstore
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "../mambaforge/lib/python3.9/site-packages/ipldstore/__init__.py", line 5, in <module>
    from .ipldstore import IPLDStore
  File "../mambaforge/lib/python3.9/site-packages/ipldstore/ipldstore.py", line 16, in <module>
    from .contentstore import ContentAddressableStore, MappingCAStore
  File "../mambaforge/lib/python3.9/site-packages/ipldstore/contentstore.py", line 12, in <module>
    from .car import read_car
  File "../mambaforge/lib/python3.9/site-packages/ipldstore/car.py", line 11, in <module>
    from .utils import is_cid_list, StreamLike, ensure_stream
  File "../mambaforge/lib/python3.9/site-packages/ipldstore/utils.py", line 9, in <module>
    from typing_extensions import TypeGuard
ImportError: cannot import name 'TypeGuard' from 'typing_extensions' (../mambaforge/lib/python3.9/site-packages/typing_extensions.py)

Proposed solution

TypeGuard has been implemented with python/typing_extensions@b7797ae and found its way into version 3.10.0.0, so I propose to increase the minimal version of typing_extensions in requirements.txt to 3.10.0.0.