Update CI script

CD into correct directory in build step

.gitlab-ci.yml

@@ -26,7 +26,7 @@ build-job:       # This job runs in the build stage, which runs first.
   image: $CI_REGISTRY/daphne4nfdi/sassena:latest
   script:
     - cmake --preset=ci .
-    - cd build
+    - cd /builds/DAPHNE4NFDI/build
     - ninja
 
 unit-test-job:   # This job runs in the test stage.