Make it works with custom inheritance column name

[gabriel-curtino]

Pull Request

Summary:
Replacing the hardcoded type attr name in the queries with the actual inherithance column name.

Testing:
Didn't add an specific test for testing it with custom inheritance columns names.

Checklist:

• Code follows the project's coding standards
• Tests have been added or updated to cover the changes
• Documentation has been updated (if applicable)
• All existing tests pass
• Conforms to the contributing guidelines

Additional Notes:

Added an extra where clause because otherwise standardrb complains about the style: lib/pay/attributes.rb:98:46: Style/HashSyntax: Don't mix styles in the same hash.