fix composer phpunit to make it work with autoloader

composer.json

@@ -7,12 +7,16 @@
         "composer/installers": "^2.0"
     },
     "require-dev": {
+        "phpunit/phpunit": "^5.7.21 || ^6.5 || ^7.5 || ^8",
         "phpcompatibility/php-compatibility": "*",
         "phpcompatibility/phpcompatibility-wp": "*",
         "squizlabs/php_codesniffer": "3.*",
-        "wp-coding-standards/wpcs": "^3.1.0",
+        "wp-coding-standards/wpcs": "dev-develop",
+        "yoast/phpunit-polyfills": "^3.0",
         "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
-        "sirbrillig/phpcs-variable-analysis": "^2.11"
+        "sirbrillig/phpcs-variable-analysis": "^2.11",
+        "phpcsstandards/phpcsextra": "^1.1.0",
+        "dms/phpunit-arraysubset-asserts": "^0.5.0"
     },
     "config": {
         "allow-plugins": true