CI try using ubuntu20.04
trying to fix broken CI builds

closes https://github.com/pandas-dev/pandas/issues/50112
BTW, I might be considering making a pre-commit hook to ban uses of latest versions of images from being used. 

There's not really much benefit to doing this, and we already pin when building wheels (I've been burned by this in the past, when Visual Studio 2017 was upgraded to Visual Studio 2019).  Thanks - jobs are passing now, so let's merge to unblock all other PRs

> BTW, I might be considering making a pre-commit hook to ban uses of latest versions of images from being used.

Nice! I'm all for automation 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 1.5.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 03a981ae61e685bb6c35234a6fb78a68373af0c6
```

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

```
git commit -am 'Backport PR #50113: CI try using ubuntu20.04'
```

4. Push to a named branch:

```
git push YOURFORK 1.5.x:auto-backport-of-pr-50113-on-1.5.x
```

5. Create a PR against branch 1.5.x, I would have named this PR:

> "Backport PR #50113 on branch 1.5.x (CI try using ubuntu20.04)"

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).
                 Can you open an issue? We should think about upgrading to 22.04.

22.10 is the latest version btw, 22.04 is just the latest version with longer support yup, here it is https://github.com/pandas-dev/pandas/issues/50115