Add others OS

Author: Aleksandr Denisyuk

.github/workflows/continuous-integration.yml

@@ -16,14 +16,15 @@ jobs:
   unit-tests:
     name: Unit tests
 
-    runs-on: ubuntu-latest
-
     strategy:
       fail-fast: false
       matrix:
+        operating-systems: [ubuntu-latest, windows-latest, macos-latest]
         php-versions: [8.1]
         stability: [prefer-lowest, prefer-stable]
 
+    runs-on: ${{ matrix.operating-systems }}
+
     steps:
       - name: Checkout
         uses: actions/checkout@v2