v1.26.1 seems broken in python 3.8

## env

```shell

bash-5.0# uname -a

Linux 85d67c49b379 5.10.25-linuxkit #1 SMP Tue Mar 23 09:27:39 UTC 2021 x86_64 GNU/Linux

bash-5.0# python --version

Python 3.8.2

```

## issue



At install there is a error:

```shell

bash-5.0# pip install yamllint==1.26.1

Collecting yamllint==1.26.1

  Using cached yamllint-1.26.1.tar.gz (126 kB)

    ERROR: Command errored out with exit status 1:

     command: /usr/bin/python3.8 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-k2ragw37/yamllint/setup.py'"'"'; __file__='"'"'/tmp/pip-install-k2ragw37/yamllint/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 /tmp/pip-install-k2ragw37/yamllint/pip-egg-info

         cwd: /tmp/pip-install-k2ragw37/yamllint/

    Complete output (5 lines):

    Traceback (most recent call last):

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

      File "/tmp/pip-install-k2ragw37/yamllint/setup.py", line 17, in <module>

        from setuptools import setup

    ImportError: cannot import name 'setup' from 'setuptools' (unknown location)

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

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

```



Seems related to the #358 

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