Change gradle to gradlew in gitlab-ci

Signed-off-by: Taylor Smock <smocktaylor@gmail.com>

.gitlab-ci.yml

@@ -135,7 +135,7 @@ build with java 13:
 java:
   stage: test
   script:
-  - gradle test
+  - ./gradlew test
   artifacts:
     reports:
       junit: build/test-results/test/**/TEST-*.xml