fix(ci): really run tests on all OS

Author: agateau-gg

.github/workflows/test-lint.yml

@@ -27,7 +27,7 @@ jobs:
           pipenv run black .
 
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]