refactor: upgrade target to Node.js 18

build-cjs.js

@@ -6,7 +6,7 @@ await esbuild.build({
   outfile: 'dist/cjs/index.cjs',
   format: 'cjs',
   platform: 'node',
-  target: ['node12'],
+  target: ['node18'],
   bundle: true,
   keepNames: true,
   external: [

package.json

@@ -25,7 +25,7 @@
     "require": "./dist/cjs/index.cjs"
   },
   "engines": {
-    "node": ">=12"
+    "node": ">=18"
   },
   "scripts": {
     "lint": "tsc && eslint ./src",