only build ca jar if job would run

cryptoanalysis/cryptoanalysis.yml

@@ -11,6 +11,10 @@ include: 'lib/docker.yml'
     DOCKER_BUILD_DIR: 'cryptoanalysis'
 
 cryptoanalysis-2.7.2-jar:
+  only:
+    changes:
+      - cryptoanalysis/*
+      - lib/docker.yml
   image: maven:3.3-alpine
   stage: build
   script: