Automatic PRs for upstream updates of PHP, FrankenPHP, and others

[kohenkatz]

Today FrankenPHP released 1.13.4, which includes some security fixes. While these updates usually get added here fairly quickly, it still requires manual action - someone has to notice the new version and create a PR.

Right now, this repository has Dependabot configured for NPM for the docs folder and for GitHub Actions.

It should be possible to configure for the major dependencies used by the package, including PHP, FrankenPHP, and probably other things too.

Right now it looks like Apache and Nginx are just whatever version is installed from the Debian repository when the image is built, but maybe there's a way to explicitly those too? Or is that going to become too complicated?

Thoughts?

[jaydrogers]

See my approach in #739 so far 😊