Remove php7.2 step in CI

Jenkinsfile

@@ -1,22 +1,6 @@
 pipeline {
  	agent none
  	stages {
- 		stage('PHP 7.2') {
- 			agent {
- 				docker {
- 					image 'php:7.2-alpine'
- 					args '-u root --privileged'
- 				}
- 			}
- 			steps {
- 				sh 'apk add --no-cache php7-phpdbg'
- 				sh 'curl -sS https://getcomposer.org/installer | php'
-				sh 'rm -f composer.lock'
- 				sh 'php composer.phar install --ignore-platform-reqs'
-				sh 'php vendor/bin/robo lint'
- 				sh 'phpdbg -qrr -- ./vendor/bin/phpunit --coverage-text --colors=never'
- 			}
- 		}
 		stage('PHP 7.3') {
 			agent {
 				docker {