[CI] Avoid pouet-it job if no HOST variable defined

Avoid CI fail for contributors

.gitlab-ci.yml

@@ -89,6 +89,6 @@ pouet-it:
     - export NC_DOWNLOAD_URL="${NC_SHARE_URL}/?path=%2F${CI_COMMIT_TAG}%2F"
     - export project="$(tr '[:lower:]' '[:upper:]' <<< ${CI_PROJECT_NAME:0:1})${CI_PROJECT_NAME:1}"
     - export MESSAGE=$(echo -e "I just released a new version of "'#'"${project}!""\n${CI_PROJECT_URL}/tags/${CI_COMMIT_TAG}\nYou can download the apks on ${NC_DOWNLOAD_URL}")
-    - carton exec ./pouet-it-from-ci.pl
+    - if [[ ! -z $HOST ]]; then carton exec ./pouet-it-from-ci.pl; fi
   only:
     - tags