add more stuff

.github/workflows/build.yml

@@ -3,8 +3,16 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    strategy:
+        matrix:
+          os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
     steps:
+        - uses: actions/checkout@v2
+          with:
+            fetch-depth: 1
+            submodules: recursive
+
         - name: Set compiler
           run: |
             cargo build -r