fix: support json format

Author: sxzz

src/core/utils.ts

@@ -1,6 +1,8 @@
 import path from 'node:path'
 
-export function getModuleFormat(id: string): 'module' | 'commonjs' | undefined {
+export function getModuleFormat(
+  id: string,
+): 'module' | 'commonjs' | 'json' | undefined {
   const ext = path.extname(id)
   switch (ext) {
     case '.mjs':
@@ -9,5 +11,7 @@ export function getModuleFormat(id: string): 'module' | 'commonjs' | undefined {
     case '.cjs':
     case '.cts':
       return 'commonjs'
+    case '.json':
+      return 'json'
   }
 }