Switch to native ACF composer repository

Since ACF now has native composer support, we should switch to that instead of using a third-party composer bridge.

https://github.com/pivvenit/acf-composer-bridge#warning-repository-shutting-down-on-1st-of-june-2023-warning
https://www.advancedcustomfields.com/resources/installing-acf-pro-with-composer/