Change release CI to use node 12 (#80)

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
-          node-version: '10.14'
+          node-version: 12
           registry-url: https://registry.npmjs.org/
       - name: Cache Node.js modules
         uses: actions/cache@v2