Toil cannot install on Setuptools 46 with the mesos extra

[adamnovak]

Because of the unmaintained pymesos -> http-parser dependency chain, as noticed in #3005 (comment), we can't install with the mesos extra now that Setuptools 46 has released with pypa/setuptools#65 which removes a deprecated component that the http-parser setup.py uses.

We need to either force setuptools <46, or fix http-parser and pymesos properly. Since they're also holding us back on support for newer Python versions, we probably need to do the second one.

┆Issue is synchronized with this Jira Task
┆Issue Number: TOIL-525

[adamnovak]

I think we fixed this both ways.