update drone.yml

drone.yml

   image: debian:stable-slim
   privileged: false
   cache:
-    - /var/cache/apt/archives
+    - /var/cache/apt
   environment:
     DEBUG: true
   commands:
     - export PATH=$PATH
+    - echo 'Acquire::http { Proxy "http://unino.de:3142"; }' | sudo tee -a /etc/apt/apt.conf.d/proxy
     - apt-get update
     - apt-get --yes upgrade
     - apt-get --yes install build-essential libc6-dev libhidapi-dev libssl-dev