change Default VectorDB Type for Sample

Author: JeffreySu

Samples/Senparc.AI.Samples.Consoles/appsettings.json

@@ -16,7 +16,7 @@
     "IsDebug": true,
     "AiPlatform": "NeuCharAI", //注意修改为自己平台对应的枚举值
     "VectorDB": {
-      "Type": "Default",
+      "Type": "InMemory",
       "ConnectionString": ""
     },
     "NeuCharAIKeys": {