* Pass PHPStan level 8
And prepare for PHPStan level 9 https://phpstan.org/user-guide/rule-levels
* Revert wrong replace in comment
* Fix PHPStan level 8
* Update PHPStan and other dev dependencies
* Remove obsolete comment
* noVariableVariables and towards bleedingEdge
https://github.com/phpstan/phpstan-strict-ruleshttps://phpstan.org/blog/what-is-bleeding-edge
* More bleedingEdge
* A bit more PHPStan level 9
* More PHPStan level 9
* Prepare for booleansInConditions
Ignore int and null
* Revert wrong line
* More fixes
* Fix keep_max_n_unread
* Stricter attribute functions
* Stricter callHooks and more PHPStan level 9
* More typing
* A tiny more
* 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
* Automated test towards PHPStan level 6
Contributes to https://github.com/FreshRSS/FreshRSS/issues/4112
With this automated tests, files that are passing Level 6 are tested to avoid regressions towards Level 5 (which is the current baseline for the whole code-base)
It is included when calling `make test-all` or can be called specifically by `composer run-script phpstan-next`
* Test and example with 3 new passing files
Efforts to reduce the resources used by CI:
* Only one git checkout
* Exclusion of irrelevant directories for several commands
* Fix some rtlcss warnings
* Move some commands from tests.yml to composer.json to make them reusasble
* Initial efforts to take avantage of all that from `make` (help welcome)