Implicit dependency on setuptools and no wheel

Attempting to install this package in an environment without setuptools pre-installed results in an error:



```

$ pip install pyrsistent

Collecting pyrsistent

  Using cached pyrsistent-0.16.0.tar.gz (108 kB)

    ERROR: Command errored out with exit status 1:

     command: /usr/local/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/c6/v7hnmq453xb6p2dbz1gqc6rr0000gn/T/pip-install-qs14zm5c/pyrsistent/setup.py'"'"'; __file__='"'"'/private/var/folders/c6/v7hnmq453xb6p2dbz1gqc6rr0000gn/T/pip-install-qs14zm5c/pyrsistent/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /private/var/folders/c6/v7hnmq453xb6p2dbz1gqc6rr0000gn/T/pip-install-qs14zm5c/pyrsistent/pip-egg-info

         cwd: /private/var/folders/c6/v7hnmq453xb6p2dbz1gqc6rr0000gn/T/pip-install-qs14zm5c/pyrsistent/

    Complete output (3 lines):

    Traceback (most recent call last):

      File "<string>", line 1, in <module>

    ModuleNotFoundError: No module named 'setuptools'

    ----------------------------------------

ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

```



Would this project consider adding a `pyproject.toml` to declare its build dependency on setuptools and also consider uploading wheels with releases?

[]