remove compatibility with node 14

Author: usu

.github/workflows/continuous-integration.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [ '14', '16', '18' ]
+        node: [ '16', '18' ]
     steps:
 
       - uses: actions/checkout@v2
@@ -56,7 +56,7 @@ jobs:
       - name: Setup node
         uses: actions/setup-node@v2
         with:
-          node-version: 14
+          node-version: 16
 
       - run: npm ci