test: fix serializer ut issue

Author: catcherwong

test/EasyCaching.UnitTests/CachingTests/CSRedisCachingProviderTest.cs

@@ -103,7 +103,7 @@ public CSRedisCachingProviderWithNamedSerTest()
 
                 }, "cs3");
 
-                option.WithJson("json").WithMessagePack("cs11").WithJson("cs2");
+                option.WithJson("json").WithMessagePack("cs11").WithJson("cs2").WithJson("cs3");
             });
 
             IServiceProvider serviceProvider = services.BuildServiceProvider();

test/EasyCaching.UnitTests/CachingTests/RedisCachingProviderTest.cs

@@ -197,7 +197,7 @@ public RedisCachingProviderWithNamedSerTest()
                     options.DBConfig.Database = 11;
                 }, "se3");
 
-                x.WithJson("json").WithMessagePack("cs11").WithJson("se2");
+                x.WithJson("json").WithMessagePack("cs11").WithJson("se2").WithJson("se3");
             });
 
             IServiceProvider serviceProvider = services.BuildServiceProvider();