assetsのjs要求時にsaltを付けないように (#4358)

* No assets salt

* remove related code

src/server/web/index.ts

@@ -55,7 +55,6 @@ router.get('/assets/*', async ctx => {
 	await send(ctx as any, ctx.path, {
 		root: client,
 		maxage: ms('7 days'),
-		immutable: true
 	});
 });