upped JVM max heap for mvn build to 2048

.gitlab-ci.yml

@@ -2,7 +2,7 @@ variables:
   POSTGRES_DB: olattest
   POSTGRES_USER: olat
   POSTGRES_PASSWORD: $SECRET_POSTGRES_PASSWORD
-  MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true -Xms512m -Xmx1024m"
+  MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true -Xms512m -Xmx2048m"
   MAVEN_CLI_OPTS: "-B --errors --fail-at-end --show-version -DinstallAtEnd=true -DdeployAtEnd=true -s .m2/settings.xml -Dhttp.proxyHost=proxy.uibk.ac.at -Dhttp.proxyPort=3128 -Dhttp.nonProxyHosts='*.uibk.ac.at'"
 
 stages: