Missing setuptools package from requirements

[decates]

Running 'pip install ratelimit', I get:

Defaulting to user installation because normal site-packages is not writeable
Collecting ratelimit
  Downloading ratelimit-2.2.1.tar.gz (5.3 kB)
    ERROR: Command errored out with exit status 1:
     command: /usr/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-ciox4c_n/ratelimit/setup.py'"'"'; __file__='"'"'/tmp/pip-install-ciox4c_n/ratelimit/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-pip-egg-info-bmunrntu
         cwd: /tmp/pip-install-ciox4c_n/ratelimit/
    Complete output (3 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
    ImportError: No module named 'setuptools'
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

It simply looks to me that setuptools is missing from the requirements.txt?
I can create a pull request for the change, but I'd have to guess which version is expected. Any suggestions?