Adds coverage report uploading for Windows

Author: gnikit

.github/workflows/main.yml

@@ -31,7 +31,10 @@ jobs:
         run: black --diff --check --verbose .
 
   coverage:
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
 
     steps:
       - uses: actions/checkout@v2