refactor!: drop node 14

Author: sxzz

tsup.config.ts

@@ -1,9 +1,9 @@
 import { defineConfig } from 'tsup'
 
 export default defineConfig({
-  entry: ['./src'],
+  entry: ['./src/index.ts'],
   format: ['cjs', 'esm'],
-  target: 'node14',
+  target: 'node16.14',
   clean: true,
   dts: true,
 })