Fix Italian fiscal code generation

[CostantiniMatteo]

There were some bugs in the generation of the fiscal code that failed validity checks in our codebase:

• The rule for the three characters in name and surname is: first the consonants, then the vowels, then pad right with Xs if the name is too short (e.g. "Xi" -> "XIX"). The generator did not follow the rule and mixed vowels and consonants. To keep the code simpler the new implementation just uses consonants, therefore only a subset of valid fiscal codes are generated. If you want, I can change it to also add vowels and account for 1 and 2 letter names.
• Birth dates could've been invalid (e.g. 2020-02-31)
• Birth day didn't account properly for female sex (male rule is to just use the day number; female rule is to add 40 to that. So allowed ranges are 1-31 and 41-71)
• The numeric part of town codes for foreign countries is in the range 100-999 and not 000-999

I didn't add any test as I don't know how to properly test those fixes besides some kind of property-based testing and fuzzing, but since it's not used in the codebase I avoided adding it. Let me know if you'd like some kind of test.

• [x] USAGE.md docs if applicable
• [x] CHANGELOG.md

[CostantiniMatteo]

Hi guys, is there anything I can do to help you merge this?

[tobyhinloopen]

I don't know italian standards so I don't know if the results are correct. However, the code LGTM.

The CI is failing for reasons not known to me, I might have to check that out.

[CostantiniMatteo]

I've never seen this "Expected — Waiting for status to be reported" but apparently a maintainer approval is needed to run the CI, so I guess after the approval the CI will run? 🤷‍♂️

Let me know if I can help!