chore: migrate customer to diesel

[vmorarian]

Description

[Provide a brief description of the changes introduced by this pull request and the motivation behind them.]

Checklist

• [ ] The code follows the project's coding conventions and style guidelines.
• [ ] All tests related to the changes have passed successfully.
• [ ] Documentation has been updated to reflect the changes (if applicable).
• [ ] All new and existing unit tests have passed.
• [ ] I have self-reviewed my code and ensured its quality.
• [ ] I have added/updated necessary comments to aid understanding.