* Complete PHPStan Level 6
Fix https://github.com/FreshRSS/FreshRSS/issues/4112
And initiate PHPStan Level 7
* PHPStan Level 6 for tests
* Use phpstan/phpstan-phpunit
* Update to PHPStan version 1.10
* Fix mixed bug
* Fix mixed return bug
* Fix paginator bug
* Fix FreshRSS_UserConfiguration
* A couple more Minz_Configuration bug fixes
* A few trivial PHPStan Level 7 fixes
* A few more simple PHPStan Level 7
* More files passing PHPStan Level 7
Add interface to replace removed class from https://github.com/FreshRSS/FreshRSS/pull/5251
* A few more PHPStan Level 7 preparations
* A few last details
* Install CssXPath with composer
* Fix code style in tests
* fix pathnames for tests and linting
* add irrelevant files to .gitignore
* Alphabetic order
* let composer sort the packages alphabetically
Co-authored-by: Alexandre Alapetite <alexandre@alapetite.fr>
