Clone submodules before build

.drone.yml

@@ -23,6 +23,10 @@ steps:
     - senpai
   commands:
   - sed -i '$s/$/,latest/' .tags
+- name: submodules
+  image: alpine/git
+  commands:
+  - git submodule update --init --recursive
 - name: build-image
   image: plugins/docker
   settings: