ci: add absolute path to phpcs executable

.gitlab-ci.yml

@@ -7,7 +7,7 @@ phpcs:
   stage: test
   script:
   - composer global require micheh/phpcs-gitlab
-  - phpcs --report=full --report-\\Micheh\\PhpCodeSniffer\\Report\\Gitlab=phpcs-quality-report.json
+  - ~/.composer/vendor/bin/phpcs --report=full --report-\\Micheh\\PhpCodeSniffer\\Report\\Gitlab=phpcs-quality-report.json
   artifacts:
     reports:
       codequality: phpcs-quality-report.json