feat: drop support for php < 8, add string types, add german translation, minor fixes

[Chris53897]

I know it is maybe a bit early for dropping php 8.
But as you are maintaining so many great bundles, it is better so be prepared.
Please have a look for BC breaks. As of course the strong types will be.

This is to fix the deprecation of NULL as Param in ltrim()
Code could be better, but it works.
https://github.com/kbond/ZenstruckRedirectBundle/compare/master...Chris53897:ZenstruckRedirectBundle:feature/drop-support-php-7.x?expand=1#diff-4ba8cd4a4825e89fd7af82dd6413ebd66fac5a052b1e1c811a147326d2578e0eR102

I thought about changing the EntityMapping from Annotations to Attributes. But this PR is already big.

[Chris53897]

I fixed files local with php-cs-fixer on mac. Now it has linting errors, which i think is maybe just an option in config.
But should be handled in a different PR.

[sadikoff]

Hi 👋🏻

Any plans to merge it?

[kbond]

Hi, sorry, missed this one. Will review today!

[kbond]

Thanks @Chris53897, released as 3.7.0.