Compatibility with pytest 5.1

[pllim]

See https://github.com/pytest-dev/pytest/releases/tag/5.1.0 . This is to fix:

E   AttributeError: 'FixtureRequest' object has no attribute 'getfuncargvalue'

Example log: https://circleci.com/gh/astropy/astropy/40431

p.s. How far back do we need to be backward compatible? Or is a simple renaming like this okay?

xref pytest-dev/pytest#2682

[bsipocz]

I don't know what to do with appveyor, it's quite annoyingly broken upstream.

[bsipocz]

The travis matrix needs to be revised, too. Sadly we don't seem to test against the latest 5.+ pytest versions...

[pllim]

I updated the Travis matrix and skipped Appveyor. 😬

[pllim]

I made the pytest warning check super strict but it still didn't catch the deprecation warning. 🤷‍♀

[bsipocz]

Yeah, not sure why it does it, I recall seeing RemovedInPytest4Warning before.

[bsipocz]

Anyway, I don't see a reason to not to merge this asap, but we need to fix the windows testing before going ahead with a new release. In the meantime, I suppose, we need to limit pytest version for the astropy CI.

[pllim]

Sounds like a plan. Thanks!

[bsipocz]

Thanks @pllim!