update node version

Node 12 has an end of life on April 30, 2022.

This PR updates the default runtime to [node16](https://github.blog/changelog/2021-12-10-github-actions-github-hosted-runners-now-run-node-js-16-by-default/), rather then node12. 

This is supported on all Actions Runners v2.285.0 or later.

.github/workflows/check-dist.yml

@@ -23,10 +23,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set Node.js 12.x
+      - name: Set Node.js 16.x
         uses: actions/setup-node@v1
         with:
-          node-version: 12.x
+          node-version: 16.x
 
       - name: Install dependencies
         run: npm ci

action.yml

@@ -198,5 +198,5 @@ outputs:
   staled-issues-prs:
     description: 'List of all staled issues and pull requests.'
 runs:
-  using: 'node12'
+  using: 'node16'
   main: 'dist/index.js'