Add `np.intc` to `_factorizers` in `pd.merge` 
- [x] closes #52451 (Replace xxxx with the GitHub issue number)
- [x] [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
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Did this fail on main as well? Couldn't reproduce on main yesterday Did not test on main. I don't have a Windows computer before next week. 

Did you test on Windows? Because I can see on Linux `np.intc == np.int32`. 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. I accidentally force-pushed the main into this branch, which was why this PR was closed.  I will open a new PR with the changes, though I will change `Int32Factorizer` to `Int64Factorizer`.