update workflows

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

.github/workflows/workflow.yml

@@ -19,10 +19,10 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
 
-      - name: Setup node 12
+      - name: Setup node 16
         uses: actions/setup-node@v2
         with:
-          node-version: 12
+          node-version: 16
           cache: npm
 
       - name: npm install

README.md

@@ -60,7 +60,7 @@ Matrix Testing:
 ```yaml
 jobs:
   build:
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         go: [ '1.14', '1.13' ]

action.yml

@@ -11,5 +11,5 @@ inputs:
     description: Used to pull node distributions from go-versions.  Since there's a default, this is typically not supplied by the user.
     default: ${{ github.token }}
 runs:
-  using: 'node12'
+  using: 'node16'
   main: 'dist/index.js'