ci: fix git submodule update (#86)

Author: AuHau

.github/workflows/update-api-docs.yaml

@@ -13,6 +13,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: true
+          fetch-depth: 0
 
       - name: Use Node.js 16
         uses: actions/setup-node@v1