adds os matrix

Author: looselycoupled

.github/workflows/release.yaml

@@ -11,14 +11,15 @@ on:
 jobs:
 
   test-suite:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         python-version: [3.6, 3.7, 3.8]
+        os: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python ${{ matrix.python-version }}
+    - name: Set up Python ${{ matrix.python-version }} ${{ matrix.os }}
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}