fix: remove cache.has function

lib/cache.ts

@@ -24,10 +24,6 @@ export function get(id: string) {
   return cache.get(id);
 }
 
-export function has(id: string) {
-  return cache.has(id);
-}
-
 export function set(id: string, content: any) {
   return cache.set(id, content);
 }