Merge pull request #181 from nicoxiang/dev

fix datetime exception

Author: catcherwong

src/EasyCaching.InMemory/Internal/InMemoryCaching.cs

@@ -107,15 +107,15 @@ public bool Add<T>(string key, T value, TimeSpan? expiresIn = null)
         {
             ArgumentCheck.NotNullOrWhiteSpace(key, nameof(key));
 
-            var expiresAt = expiresIn.HasValue ? SystemClock.UtcNow.SafeAdd(expiresIn.Value) : DateTime.MaxValue;
+            var expiresAt = expiresIn.HasValue ? SystemClock.UtcNow.SafeAdd(expiresIn.Value) : DateTimeOffset.MaxValue;
             return SetInternal(new CacheEntry(key, value, expiresAt), true);
         }
 
         public bool Set<T>(string key, T value, TimeSpan? expiresIn = null)
         {
             ArgumentCheck.NotNullOrWhiteSpace(key, nameof(key));
 
-            var expiresAt = expiresIn.HasValue ? SystemClock.UtcNow.SafeAdd(expiresIn.Value) : DateTime.MaxValue;
+            var expiresAt = expiresIn.HasValue ? SystemClock.UtcNow.SafeAdd(expiresIn.Value) : DateTimeOffset.MaxValue;
             return SetInternal(new CacheEntry(key, value, expiresAt));
         }