adjust drone config

.drone.yml

@@ -4,16 +4,6 @@ type: docker
 name: default
 
 steps:
-  - name: restore-cache
-    image: drillster/drone-volume-cache
-    volumes:
-      - name: cache
-        path: /cache
-    settings:
-      restore: true
-      mount:
-        - ~/.cache/pip
-
   - name: build
     image: plugins/docker:latest
     volumes:
@@ -33,16 +23,6 @@ steps:
       mirror: https://5c492fmo.mirror.aliyuncs.com
       dockerfile: ./Dockerfile
 
-  - name: rebuild-cache
-    image: drillster/drone-volume-cache
-    volumes:
-      - name: cache
-        path: /cache
-    settings:
-      rebuild: true
-      mount:
-        - ~/.cache/pip
-
   - name: scp
     image: appleboy/drone-scp
     settings: