pip install does not install version-qualified package

[phmccarty]

When collecting PyPI metadata for PyPI package provides/requires, autospec runs pip install PACKAGE in a virtualenv. Instead, it should be running pip install PACKAGE==VERSION for the target package version.

This will fix issues that occasionally appear when a package is intentionally older than latest (e.g. Django remaining on the LTS series), and it will help avoid invalid queries when naming clashes exist between PyPI and other ecosystems (e.g. meld is a GNOME package, and a different project named meld is a PyPI package, and both use setuptools to build).

[phmccarty]

I posted a possible solution for this issue to a branch:

https://github.com/phmccarty/autospec/commits/issue652

I'm not sure about this approach though, so I'll leave it there for now.