Run on all gha OSes

Author: oli-obk

.github/workflows/ci.yaml

@@ -9,11 +9,14 @@ on:
 
 jobs:
   rust-test:
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
       - name: Run cargo test
         uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --all
+          args: --all