chore: require node14+ (#83)

Author: yoshinorin

Diff for: .github/workflows/tester.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        node-version: ['12.x', '14.x']
+        node-version: ['14.x', '16.x', '18.x']
       fail-fast: false
     steps:
       - uses: actions/checkout@v2

Diff for: package.json

@@ -16,7 +16,7 @@
     "lib/"
   ],
   "engines": {
-    "node": ">=12.9.0"
+    "node": ">=14"
   },
   "repository": "hexojs/hexo-generator-index",
   "homepage": "https://hexo.io/",