install curl before using in CI

.gitlab-ci.yml

@@ -33,5 +33,7 @@ build_nginx:
 deploy:
   stage: test_deploy
   when: manual
+  before_script:
+    - apk add --update curl && rm -rf /var/cache/apk/*
   script:
     - curl -X POST https://portainer.intranet.pirati.cz/api/webhooks/5af05c61-4435-40b5-9afe-0a7906743238