Add optional time crate support for apalis-sql

I want to use sqlx with the time crate but apalis-sql hardcodes chrono. I added time crate support as an optional feature in my fork - chrono stays as the default so it's fully backwards compatible.

This would require changes in at least apalis-postgres (that's what I use). Are there other parts of the project that would need updating too?

Would you be open to a PR for this?