Pin down to compatible coding-standard dependency

[galfit82]

Fixes errors occuring due to changed interfaces in recent slevomat/coding-standard ^8.0 releases.

[b3nl]

May I ask, what happend? What is the intention? I personally use it for example with slevomat 8.13.4 and it looks good. @galfit82

[galfit82]

@b3nl here's the error we get when running phpcs with newer slevomat versions:

phpcbf     -d memory_limit=1024M     --standard=./tools/config/phpcs.xml     ./src/custom/static-plugins
PHP Fatal error:  Uncaught Error: Call to undefined method SlevomatCodingStandard\Helpers\AnnotationHelper::getAnnotationsByName() in /root/tools/PHP_CodeSniffer/src/Standards/BestIt/Sniffs/TypeHints/ExplicitAssertionsSniff.php:85
Stack trace:
#0 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/src/Files/File.php(498): BestIt\Sniffs\TypeHints\ExplicitAssertionsSniff->process()
#1 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/src/Files/LocalFile.php(92): PHP_CodeSniffer\Files\File->process()
#2 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/src/Runner.php(632): PHP_CodeSniffer\Files\LocalFile->process()
#3 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/src/Runner.php(438): PHP_CodeSniffer\Runner->processFile()
#4 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/src/Runner.php(204): PHP_CodeSniffer\Runner->run()
#5 /root/tools/PHP_CodeSniffer/vendor/squizlabs/php_codesniffer/bin/phpcbf(18): PHP_CodeSniffer\Runner->runPHPCBF()
#6 /root/tools/PHP_CodeSniffer/vendor/bin/phpcbf(119): include('...')
#7 {main}
  thrown in /root/tools/PHP_CodeSniffer/src/Standards/BestIt/Sniffs/TypeHints/ExplicitAssertionsSniff.php on line 85