CI: Install libegl explicitly for pytest-qt on ubuntu
Seems like ubuntu CI images don't include this anymore e.g. https://github.com/pandas-dev/pandas/actions/runs/10253907588/job/28367579964
This allows the tests to run again so merging 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 2.2.x
git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
git cherry-pick -x -m1 81a12ddd270fc3bbed4e6c49098d3a5f37dfef77
```

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

```
git commit -am 'Backport PR #59423: CI: Install libegl explicitly for pytest-qt on ubuntu'
```

4. Push to a named branch:

```
git push YOURFORK 2.2.x:auto-backport-of-pr-59423-on-2.2.x
```

5. Create a PR against branch 2.2.x, I would have named this PR:

> "Backport PR #59423 on branch 2.2.x (CI: Install libegl explicitly for pytest-qt on ubuntu)"

And apply the correct labels and milestones.

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

Remember to remove the `Still Needs Manual Backport` label once the PR gets merged.

If these instructions are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                