fix: apply type: module only to runtime modules

Author: pieh

src/build/functions/server.ts

@@ -87,7 +87,7 @@ const writeHandlerManifest = async (ctx: PluginContext) => {
 
 const writePackageMetadata = async (ctx: PluginContext) => {
   await writeFile(
-    join(ctx.serverHandlerRootDir, 'package.json'),
+    join(ctx.serverHandlerDir, '.netlify', 'package.json'),
     JSON.stringify({ type: 'module' }),
   )
 }