Add loockup table validation

[iurisevero]

Proposed changes:

• Resolve issue Log warning if lookup tables are not used correctly #5956
• Update the _add_lookup_table_regexes function, at (regex_featurizer.py)[https://github.com/RasaHQ/rasa/blob/1.10.x/rasa/nlu/featurizers/sparse_featurizer/regex_featurizer.py], to verify if there is some table in the training data.loockup_tables and return a bool informing it
• Print a warning message if validation returns false

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• updated the changelog (please check changelog for instructions)
• reformat files using black (please check Readme for instructions)

[sara-tagger]

Thanks for submitting a pull request 🚀 @yennycheung will take a look at it as soon as possible ✨

[yennycheung]

Thank you for your contribution @iurisevero. The solution looks great. Would you mind pointing the pull request to main instead of RasaHQ:1.10.x? Then we could include your changes in the next releases. Thank you!

[iurisevero]

Hi @yennycheung, I'll change the pointing, no problem! But I don't think the CI will accept my changes, because I did them from the tag 1.10.23, once the issue was solved in 2.x versions but still happening at 1.10.x.

[yennycheung]

Apologies for the late reply, it seems like there are a lot of unrelated changes, would you mind pulling the latest main and cherry-picking your changes against it?

[iurisevero]

Hi. Don't worry. So, I don't think that pulling the latest main is a good idea. As I said, my changes were made for the 1.10.x version, where this issue still relevant. On the 2.x versions it was already solved.

My idea was to merge these changes to 1.10.x branch and fix this problem for the next 1.10 tag.
Does that make sense for you?

[yennycheung]

@wochinge, do we do patches over the older versions or Rasa OSS?

[wochinge]

We only do so if it's crucial. Rasa Open Source 2 is out since more than half a year and I'd highly encourage to switch to it. We unfortunately don't have the capacity to maintain two majors side by side at the moment.

[iurisevero]

I get it. I believe this pull request will be closed so, right?
I suggest closing the issue #5956 as well. It doesn't make sense anymore.

[yennycheung]

@iurisevero, thank you for your help on this one. Hope next time we can get your work merged! 🙏🏼