Add gemini models

Author: intitni

Tool/Sources/Preferences/Types/GoogleGenerativeChatModel.swift

@@ -1,6 +1,8 @@
 import Foundation
 
 public enum GoogleGenerativeAIModel: String {
+    case gemini15Pro = "gemini-1.5-pro"
+    case gemini15Flash = "gemini-1.5-flash"
     case geminiPro = "gemini-pro"
 }
 
@@ -9,6 +11,10 @@ public extension GoogleGenerativeAIModel {
         switch self {
         case .geminiPro:
             return 32768
+        case .gemini15Flash:
+            return 1_048_576
+        case .gemini15Pro:
+            return 2_097_152
         }
     }
 }