Remove setuptools version restrictions

[kmaehashi]

setuptools 42.0.x seems to have an issue with Python 3.8: wheel (cache) build failures are not handled correctly when installing dependency packages (the error should be silently ignored if wheel is not installed, but the entire installation fails).

pypa/setuptools#1934

Workaround: do pip install wheel or pip install 'setuptools<42' (#541, #563)

[kmaehashi]

15:49:51     WARNING: The wheel package is not available.
15:49:51       ERROR: Command errored out with exit status 1:
15:49:51        command: /opt/pyenv/versions/3.8.0/bin/python3.8 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-wheel-wxrqw0v6/fastrlock/setup.py'"'"'; __file__='"'"'/tmp/pip-wheel-wxrqw0v6/fastrlock/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d /tmp/pip-wheel-_k_ert04
15:49:51            cwd: /tmp/pip-wheel-wxrqw0v6/fastrlock/
15:49:51       Complete output (7 lines):
15:49:51       building without Cython
15:49:51       usage: setup.py [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
15:49:51          or: setup.py --help [cmd1 cmd2 ...]
15:49:51          or: setup.py --help-commands
15:49:51          or: setup.py cmd --help
15:49:51     
15:49:51       error: invalid command 'bdist_wheel'