Requires Python 3.11 or later due to dependency upon dataclass_transform#1

Thank you for creating this package! I found this issue whilst attempting to use your [python-debouncer](https://github.com/sassanh/python-debouncer) package, which looks ideal for my project needs. Unfortunately it appears that `dataclass_transform` requires Python 3.11 or later, and since `python-debouncer` depends upon `python-immutable`, that is affected too. # Expected behaviour The requirements state "Python 3.9 or later", so I expected to be able to use this package for an application running on Python 3.10. # Actual behaviour When using this dependency on Python 3.10, I get the following error: ``` Traceback (most recent call last): ...snip... File "/home/snip/python3.10/site-packages/debouncer/__init__.py", line 1, in <module> from .debounce import debounce, DebounceOptions File "/home/snip/python3.10/site-packages/debouncer/debounce.py", line 22, in <module> from immutable import Immutable File "/home/snip/python3.10/site-packages/immutable/__init__.py", line 1, in <module> from .main import * File "/home/snip/python3.10/site-packages/immutable/main.py", line 5, in <module> from typing import ( ImportError: cannot import name 'dataclass_transform' from 'typing' (/usr/lib/python3.10/typing.py) ``` From looking at [PEP 681](https://peps.python.org/pep-0681/), it appears `dataclass_transform` was not added until Python 3.11?