BUG: Fix DateFrameGroupBy.mean error for Int64 dtype
- [x] closes #32219
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

It looks like this was due to the `TypeError` not being caught
also merge master 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 9e7cb7c102655d0ba92d2561c178da9254d5cef5
```

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

```
$ git commit -am 'Backport PR #32223: BUG: Fix DateFrameGroupBy.mean error for Int64 dtype'
```

4. Push to a named branch :

```
git push YOURFORK 1.0.x:auto-backport-of-pr-32223-on-1.0.x
```

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

> "Backport PR #32223 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).
                 thanks @dsaxton  @dsaxton if you can try a manual backport would be great :-> Thanks @dsaxton. FYI, in the future you can remove the "still needs manual backport" label after the backport is merged.