feat: Add Latvian translations for validation error messages

[Albertbol]

Connection with issue(s)

Solution description

Screenshots or Videos

To Do

• [x] Read contributing guide
• [ ] Check the original issue to confirm it is fully satisfied
• [ ] Add solution description to help guide reviewers
• [ ] Add unit test to verify new or fixed behaviour
• [x] If apply, add documentation to code properties and package readme

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.20%. Comparing base (0e6f8c3) to head (968d188). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #132 +/- ## ======================================= Coverage 99.20% 99.20% ======================================= Files 95 95 Lines 1011 1011 ======================================= Hits 1003 1003 Misses 8 8 ``` | [Flag](https://app.codecov.io/gh/flutter-form-builder-ecosystem/form_builder_validators/pull/132/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flutter-form-builder-ecosystem) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/flutter-form-builder-ecosystem/form_builder_validators/pull/132/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flutter-form-builder-ecosystem) | `99.20% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flutter-form-builder-ecosystem#carryforward-flags-in-the-pull-request-comment) to find out more.

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