Update ci.yml

Author: georgeboot

.github/workflows/ci.yml

@@ -58,6 +58,9 @@ jobs:
     name: Jest
     steps:
       - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '15'
       - name: Install dependencies
         run: yarn install
       - name: Run Jest