feat: add ua postal code

[VoloshchenkoAl]

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Description

This PR adds a new regex for the Ukrainian postal code in the PostalCode scalar.

Refferance: https://en.wikipedia.org/wiki/Postal_codes_in_Ukraine

Ukraine uses five-digit numeric postal codes that are written immediately to the right of the city or settlement name.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have followed the CONTRIBUTING doc and the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests and linter rules pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...