Update build.yml

Author: actboy168

.github/workflows/build.yml

@@ -21,6 +21,10 @@ jobs:
   resource:
     runs-on: ubuntu-latest
     steps:
+    - uses: actions/checkout@v1
+      with:
+        ref: refs/heads/master
+        submodules : recursive
     - uses: actions/upload-artifact@v2
       with:
         name: lua-language-server