chore github action change to nyc and run test once

Author: lihsai0

.github/workflows/ci-test.yml

@@ -19,12 +19,12 @@ jobs:
       - name: Setup dependencies
         run: |
           npm install
-          npm install -g istanbul
+          # nyc@14 support nodejs >= 6
+          npm install -g nyc@14
       - name: Run cases
         run: |
           npm run check-type
-          npm test
-          istanbul cover ./node_modules/mocha/bin/_mocha --reporter test -- -R spec
+          nyc --reporter=lcov npm test
         env:
           QINIU_ACCESS_KEY: ${{ secrets.QINIU_ACCESS_KEY }}
           QINIU_SECRET_KEY: ${{ secrets.QINIU_SECRET_KEY }}