add defaulted-constructor for cache which got implicitly deleted by deleting the copy constructor

offloading-cacher/cache.hpp

@@ -237,6 +237,7 @@ namespace dsacache {
         std::unique_ptr<CacheData> GetFromCache(uint8_t* src, const size_t size, const int dst_node);
 
     public:
+        Cache() = default;
         Cache(const Cache& other) = delete;
 
         // initializes the cache with the two policy functions