Attempt to add PHPStan messages to CI

Jenkinsfile

@@ -35,7 +35,12 @@ pipeline {
 			}
 		}
 		stage('Code Cleanliness') {
-			agent any
+			agent {
+				docker {
+					image 'php:8-cli-alpine'
+					args '-u root --privileged'
+				}
+			}
 			steps {
 				sh "php ./vendor/bin/phpstan analyse src/ -c phpstan.neon -n --no-ansi --no-progress --error-format=checkstyle > build/logs/checkstyle.xml"
 				recordIssues(tools: [checkstyle(reportEncoding: 'UTF-8')])