ENH: set __module__ on IndexSlice
- [ ] Part of #55178
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

@jorisvandenbossche this one is a bit different? i'll try something that does give the correct output and is technically correct but we'll see what else breaks!

```
>>> pd.IndexSlice
<pandas.IndexSlice object at 0x7f2528c70d60>
``` > i'll try something that does give the correct output and is technically correct

in jupyter notebook the output is `<pandas.IndexSlice at 0x7f2d681cd870>`

> but we'll see what else breaks!

seems fine so far except for the pre-commit error This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.