Update '.drone.yml'

.drone.yml

@@ -17,5 +17,7 @@ steps:
         - eval "$(ssh-agent -s)"
         - mkdir -p ~/.ssh
         - echo $SSH_PRIV > ~/.ssh/id_ed25519
+        - chmod 600 ~/.ssh/id_ed25519
+        - chmod 644 ~/.ssh/id_ed25519.pub
         - echo $SSH_PUB > ~/.ssh/id_ed25519.pub
         - ssh-add ~/.ssh/id_ed25519