CI should use 7.2 for testing, add 7.2 to validation

.gitlab-ci.yml

@@ -6,6 +6,12 @@ stages:
 before_script:
   - bash ci/docker_install.sh > /dev/null
 
+validate:7.2:
+  image: php:7.2
+  stage: validate
+  script:
+    - bash ci/php_lint.sh ./
+
 validate:7.1:
   image: php:7.1
   stage: validate
@@ -55,8 +61,8 @@ test:7.1:
     - cd Tests
     - phpunit
 
-test:7.0:
-  image: php:7.0
+test:7.2:
+  image: php:7.2
   stage: test
   script:
     - cd api