CI: remove xfail for numpy-dev on branch 1.1.x only
partially reverts pandas-dev/pandas#35537, xref https://github.com/pandas-dev/pandas/issues/35481#issuecomment-705144719
Not sure why still needed on master looks like test_loc_setitem_empty_append_raises still fails. will update tomorrow. just the travis-36-cov failures. this build was until recently timing out 100% of the time, it's now apparent there are a few errors there that need investigation.

Linux py37_np_dev passing so merging. > just the travis-36-cov failures. this build was until recently timing out 100% of the time, it's now apparent there are a few errors there that need investigation.

opened #37309 for this.