Run tests using bash explicitly

Author: hosaka

.github/workflows/main.yml

@@ -55,7 +55,7 @@ jobs:
       - name: Test all python/qt combinations
         uses: coactions/setup-xvfb@v1
         with:
-          run: ./testall.sh
+          run: bash ./testall.sh
 
   # combine-coverage:
   #   needs: tests