ci: add GIT_SUBMODULE_STRATEGY for vendor dependencies

.gitlab-ci.yml

@@ -17,6 +17,9 @@ stages:
   - deploy
 
 variables:
+  # Submodules — discord.js-selfbot-v13 and discord-video-stream
+  GIT_SUBMODULE_STRATEGY: recursive
+
   REGISTRY: $CI_REGISTRY
   REGISTRY_PROJECT: $CI_REGISTRY/$CI_PROJECT_PATH
   IMAGE_TAG_COMMIT: $CI_COMMIT_SHA