Specify bash shell in test workflow for cross-platform support

Author: scriptype

.github/workflows/tests.yml

@@ -20,6 +20,7 @@ jobs:
     - name: install dependencies
       run: npm ci
     - name: run tests
+      shell: bash
       run: for i in {1..4}; do npm run test:ci || exit 1; done
     - name: Coveralls
       uses: coverallsapp/github-action@v2