fix: only run one job at a time per branch

.gitlab-ci.yml

@@ -34,6 +34,7 @@ stages:
 
 build:
   stage: build
+  resource_group: ${CI_COMMIT_BRANCH} # this prevents parallel (potentially racy) pipeline runs
   script:
     - mkdir -p latest
     - "(curl -LsS --header 'PRIVATE-TOKEN: ${CI_JOB_TOKEN}' https://${CI_SERVER_HOST}/${CI_PROJECT_NAMESPACE}/${CI_PROJECT_NAME}/-/jobs/artifacts/${CI_COMMIT_BRANCH}/download?job=build | bsdtar -xf - -C latest) || true"