chore: reduce test matrix

.github/workflows/ci.yml

@@ -15,10 +15,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Use Node.js 14.x for lint
+    - name: Use Node.js 16.x for lint
       uses: actions/setup-node@v1
       with:
-        node-version: '14.x'
+        node-version: '16.x'
     - run: npm i
     - run: npm run lint
 
@@ -28,7 +28,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x]
+        node-version: [16.x]
 
     env:
       NODE_ENV: test
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x]
+        node-version: [16.x]
 
     env:
       NODE_ENV: test