CI: fix feather test
updated to use external_error_raised.  Do we want to check anything about the message being reasonable? > updated to use external_error_raised. Do we want to check anything about the message being reasonable?

I don't think we do, as this is an external error message.
But I would like to hear others as well. Thanks @jbrockmendel yea I don't think we need to test for 8 different messages! 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 1.0.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 6d3cc14fc52685511329cedf1e11d15651ac6a8e
```

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

```
$ git commit -am 'Backport PR #31791: CI: fix feather test'
```

4. Push to a named branch :

```
git push YOURFORK 1.0.x:auto-backport-of-pr-31791-on-1.0.x
```

5. Create a PR against branch 1.0.x, I would have named this PR:

> "Backport PR #31791 on branch 1.0.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](https://github.com/MeeseeksBox/MeeseeksDev).
                 Hmm I guess that helper isn't available on the 1.0.x branch why exactly was this merged @WillAyd @jbrockmendel @jorisvandenbossche  was this fixing a CI issue?

it is not about testing for the error messages, but the fact that the error messages are *different* that is extremely troubling. This is de-facto removing legitimate tests.
 Yea looks to have failed CI I think alternately would have to add a 9th error message to test for with current design; maybe should break up and test error message specifically by reader? msg4 doesn't look like an external message. should external_error_raised fail this? @MomIsBestFriend  not at a computer to check though. so could be external. just looks like one of ours. > msg4 doesn't look like an external message. 

Yes, I think that is the only one raised by ourselves (it's "path_or_buf needs to be a string file path or file-like"). But it's actually also a wrong error message we were testing .. as what is passed *is* a string file path) > msg4 doesn't look like an external message. should external_error_raised fail this? @MomIsBestFriend

@simonjayhawkins ```tm.external_error_raised``` is an alias for 
```pytest.raises(<An exception class>, match=None)```.

It does not check for whether or not this is an actual external error message. 