TST: Fix egg_info job not running

[pllim]

Fix #395

[weaverba137]

I'm looking at the Travis documentation and as far as I can tell having a matrix section inside a env section is still valid. Is there any documentation to the contrary?

[pllim]

I didn't dig too hard at their doc. I simply implementing here what worked for my use case. I suspect not too far in the future, we won't be using Travis altogether.

https://www.reddit.com/r/programming/comments/atjltu/layoffs_at_travis_ci_their_team_was_being/

[bsipocz]

Thanks @pllim!