ci: runs windows tests on all branches

Author: joelgallant

.github/workflows/main.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         node-version: [14.x]
 
     steps:
@@ -26,6 +26,7 @@ jobs:
     - run: yarn test --coverage
       env: { CI: 1 }
     - uses: codecov/codecov-action@v1
+      if: matrix.os == 'ubuntu-latest'
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
         files: |