Upgrade 2.1.0 To Latest 2.x.x - Php Question

Just purchased another year of CS-Cart upgrades.

Our cart is 2.1.x, and will be getting our system slowly updated.

One of the reasons for updating is moving to a later (supported) version of PHP.

Is there a guideline or maybe someone knows (as I can't find it in the release notes here [url=“Version History — CS-Cart 4.15.x documentation”]https://www.cs-cart.com/cscart-changelog.html[/url]) when PHP v5.3.x was supported? Or v5.4.x?

Thanks for any help and insight!