Don't use pandas 0.25.0 for testing

[dstansby]

Thanks @bingyao for putting in a quick fix here: #14860; I think blacklisting pandas 0.25.0 is the correct long term thing to do however, as a fix (pandas-dev/pandas#27481) should hopefully go into 0.25.1

[jklymak]

Yeah if we think we can fix in pandas.

[timhoffm]

appveyor still fails test_bar_pandas with

TypeError: the dtypes of parameters x (datetime64[ns]) and width (int32) are incompatible

[dstansby]

@meeseeksdev backport to v3.1.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

$ git checkout v3.1.x
$ git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

$ git cherry-pick -m1 e5b4f79c6a4897895ad32d5b789b43e206d7a53c

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

$ git commit -am "Backport PR #14861: Don't use pandas 0.25.0 for testing"

4. Push to a named branch :

git push YOURFORK v3.1.x:auto-backport-of-pr-14861-on-v3.1.x

5. Create a PR against branch v3.1.x, I would have named this PR:

"Backport PR #14861 on branch v3.1.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to suggest an improvement.

[timhoffm]

Backported in dec7c67