ci: prepare submodules.

Signed-off-by: Yilin Sun <imi415@imi.moe>

.drone.yml

@@ -7,11 +7,15 @@ pool:
   use: do-docker-20-04
 
 steps:
-- name: Build
+- name: submodules
+  commands:
+  - git submodule update --init --recursive
+
+- name: build
   commands:
   - docker buildx build -t ntripcaster .
 
-- name: Image Preparation
+- name: image preparation
   environment:
     REGISTRY_USER:
       from_secret: docker_user
@@ -22,7 +26,7 @@ steps:
     - docker tag ntripcaster git.minori.work/embedded_sdk/ntripcaster:0.1.5
     - docker login -u $REGISTRY_USER -p $REGISTRY_PASS git.minori.work
 
-- name: Push
+- name: push
   commands:
     - docker push git.minori.work/embedded_sdk/ntripcaster:latest
     - docker push git.minori.work/embedded_sdk/ntripcaster:0.1.5