enhancement: Transak getURL input validation

[jeeanribeiro]

Summary

Improves Transak getURL input validation

Testing

Platforms

• Desktop
  • MacOS
  • Linux
  • Windows

Checklist

• I have followed the contribution guidelines for 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 added or modified tests that prove my changes work as intended
• I have verified that new and existing unit tests pass locally with my changes
• I have verified that my latest changes pass CI workflows for testing and linting
• I have made corresponding changes to the documentation