Update '.drone.yml'

.drone.yml

@@ -16,8 +16,8 @@ steps:
         - apt-get install openssh-client -y
         - eval "$(ssh-agent -s)"
         - mkdir -p ~/.ssh
-        - echo $SSH_PRIV > ~/.ssh/id_rsa
-        - echo $SSH_PUB > ~/.ssh/id_rsa.pub
+        - echo "$SSH_PRIV" > ~/.ssh/id_rsa
+        - echo "$SSH_PUB" > ~/.ssh/id_rsa.pub
         - chmod 600 ~/.ssh/id_rsa
         - chmod 644 ~/.ssh/id_rsa.pub
         - cat ~/.ssh/id_rsa.pub