Added image declaration for the test phase and renamed release to deploy

Signed-off-by: Louis Vallat <louis@louis-vallat.xyz>

.gitlab-ci.yml

@@ -5,7 +5,7 @@ services:
 stages:
   - build
   - test
-  - release
+  - deploy
 
 # Disable the Gradle daemon for Continuous Integration servers as correctness
 # is usually a priority over speed in CI environments. Using a fresh
@@ -34,6 +34,7 @@ build:
 
 
 test:
+  image: gradle:jdk15
   stage: test
   script: gradle check
   cache:
@@ -45,7 +46,7 @@ test:
 
 
 package:
-  stage: release
+  stage: deploy
   variables: 
     IMAGE_LATEST_TAG: $CI_REGISTRY_IMAGE:latest
     IMAGE_COMMIT_REF_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG