BUG: able to create nonexistent Timestamp
- [X] closes #41072 
- [X] tests added / passed
- [X] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [X] whatsnew entry

Upon seeing Github Actions CI, we seem to have a couple of issues with other test cases that invoke methods that eventually invoke the creation of a new timestamp in which one of their timestamps is nonexistent. For one of these, a `nonexistent = 'shift_forward'` parameter in `tz_localize` isn't accounted for in `__new__` and in another, nonexistent isn't directly accounted for in any parameters. A possible way to resolve this would be adding a `nonexistent` parameter to `Timestamp` or potentially to `__new__` that defaults at "raise", but I haven't had a lot of time to think through the feasibility of that. Let me know how you think we should address this. > A possible way to resolve this would be adding a nonexistent parameter to Timestamp or potentially to __new__ that defaults at "raise", but I haven't had a lot of time to think through the feasibility of that. Let me know how you think we should address this.

We're pretty reticent to add new args to `Timestamp.__new__`, i think always raising is fine This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. Thanks for the PR, but it appears that it has gone stale and needs to address the reviews. Going to close due to inactivity but let us know if you'd like to continue and we can reopen.