CI: set NODE_OPTIONS in the docker file

.gitlab-ci.yml

 image: registry.gitlab.tugraz.at/dbp/topics/signature/main:v1
 
-variables:
-  NODE_OPTIONS: '--max-old-space-size=4096'
-
 cache:
   key: $CI_PROJECT_PATH
   paths:

.gitlab-ci/Dockerfile

@@ -41,4 +41,7 @@ RUN mkdir -p "${COMPOSER_HOME}"
 ADD composer.lock "${COMPOSER_HOME}"
 ADD composer.json "${COMPOSER_HOME}"
 RUN composer global install
-ENV PATH "${COMPOSER_HOME}/vendor/bin:${PATH}"
\ No newline at end of file
+ENV PATH "${COMPOSER_HOME}/vendor/bin:${PATH}"
+
+# https://stackoverflow.com/questions/53230823
+ENV NODE_OPTIONS '--max-old-space-size=2048'