fix File.Create on Init() not disposed (#532)

Author: dplarina

src/EasyCaching.Disk/DefaultDiskCachingProvider.cs

@@ -115,7 +115,7 @@ private void Init()
 
             if (!File.Exists(path))
             {
-                File.Create(path);
+                using (File.Create(path)) {}
             }
 
             InitCacheKey();