remove explicit fs location

.drone.yml

@@ -10,7 +10,7 @@ steps:
     restore: true
     cache_key: "{{ .Repo.Name }}"
     archive_format: "gzip"
-    filesystem_cache_root: "/tmp/cache"
+    #filesystem_cache_root: "/tmp/cache"
     mount:
       - '.pipcache'
   volumes:
@@ -35,7 +35,7 @@ steps:
     rebuild: true
     cache_key: "{{ .Repo.Name }}"
     archive_format: "gzip"
-    filesystem_cache_root: "/tmp/cache"
+    #filesystem_cache_root: "/tmp/cache"
     mount:
       - '.pipcache'
 
@@ -62,5 +62,4 @@ steps:
 
 volumes:
   - name: cache
-    host:
-      path: /tmp/cache
+    tmp: {}