drone custom ssh git clone: b64 key

.drone.yml

@@ -11,11 +11,12 @@ steps:
   - name: clone
     image: cirrusci/flutter:dev
     environment:
-      buildbot_key:
-          from_secret: buildbot_key
+      buildfiles_key_b64:
+          from_secret: buildfiles_key_b64
     commands:
       - mkdir ~/.ssh
-      - echo $buildbot_key > ~/.ssh/id_rsa
+      - echo buildfiles_key_b64 > ~/.ssh/id_rsa.b64
+      - base64 --decode ~/.ssh/id_rsa.b64 > ~/.ssh/id_rsa
       # force by pass of ssh host key check, less secure
       - ssh-keyscan -H build.openprivacy.ca >> ~/.ssh/known_hosts
       - git clone gogs@git.openprivacy.ca:flutter/flutter_app.git .