Bump actions/setup-node from v1 to v2.1.5 (#73)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2.1.5
       with:
         node-version: ${{ matrix.node-version }}
     - name: Install Dependencies