fix: Node.js 9 nyc version

Author: Phillip9587

.github/workflows/ci.yml

@@ -88,7 +88,7 @@ jobs:
 
         - name: Node.js 9.x
           node-version: "9.11"
-          npm-i: mocha@7.2.0 supertest@6.1.6
+          npm-i: mocha@7.2.0 nyc@14.1.1 supertest@6.1.6
 
         - name: Node.js 10.x
           node-version: "10.24"