Use wp-cli-tests v5

Author: swissspidy

composer.json

@@ -22,7 +22,7 @@
     },
     "require-dev": {
         "roave/security-advisories": "dev-latest",
-        "wp-cli/wp-cli-tests": "^4"
+        "wp-cli/wp-cli-tests": "^5"
     },
     "extra": {
         "branch-alias": {
@@ -42,19 +42,22 @@
     "config": {
         "allow-plugins": {
             "dealerdirect/phpcodesniffer-composer-installer": true,
-            "johnpbloch/wordpress-core-installer": true
+            "johnpbloch/wordpress-core-installer": true,
+            "phpstan/extension-installer": true
         }
     },
     "scripts": {
         "behat": "run-behat-tests",
         "behat-rerun": "rerun-behat-tests",
         "lint": "run-linter-tests",
         "phpcs": "run-phpcs-tests",
+        "phpstan": "run-phpstan-tests",
         "phpunit": "run-php-unit-tests",
         "prepare-tests": "install-package-tests",
         "test": [
             "@lint",
             "@phpcs",
+            "@phpstan",
             "@phpunit",
             "@behat"
         ]