Remove temporary key file and pipe key to gpg

.gitlab-ci.yml

@@ -5,13 +5,10 @@ main:
     - apt-get update
     - apt-get install -y gnupg2
     - date > message
-    - echo "$GPG_KEY" > key.asc
-    - cat key.asc
-    - gpg --import key.asc || true
-    - gpg --detach-sign -a message || true
+    - echo "$GPG_KEY" | gpg --import key.asc
+    - gpg --detach-sign -a message
 
   artifacts:
     expire_in: 1 day
     paths:
      - "message*"
-     - "key.asc"