CI: Min Pytest Cov Version/Restrict xdist version
- [x] closes #35737
Travis was successful, although I'm not sure why 2.10.1 isn't pulled in without this change. Any idea there? cc @jreback issue created for unpin: https://github.com/pandas-dev/pandas/issues/35756 Thanks @alimcmaster1  @meeseeksdev backport 1.1.x

