[fix] iterable error when use gemini-pro (#277)

# PR Checklist
- [ ] Did you check if it works normally in all models? *ignore this
when it dosen't uses models*
- [x] Did you check if it works normally in all of web, local and node
hosted versions? if it dosen't, did you blocked it in those versions?
- [ ] Did you added a type def?

# Description
An error occurred when use gemini-pro model with disabled Vertex-AI:

![img](https://github.com/kwaroran/RisuAI/assets/35911521/e3e2cc5a-8fe8-4661-ba5b-317c5700eb86)

src/ts/process/request.ts

@@ -1194,8 +1194,7 @@ export async function requestChatDataMain(arg:requestDataArgument, model:'model'
 
             let fullRes = ''
 
-            for(const data of res.data){
-
+            const processDataItem = (data:any) => {
                 if(data?.candidates?.[0]?.content?.parts?.[0]?.text){
                     fullRes += data.candidates[0].content.parts[0].text
                 }
@@ -1213,6 +1212,15 @@ export async function requestChatDataMain(arg:requestDataArgument, model:'model'
                 }
             }
 
+            // traverse responded data if it contains multipart contents
+            if (typeof (res.data)[Symbol.iterator] === 'function') {
+                for(const data of res.data){
+                    processDataItem(data)
+                }
+            } else {
+                processDataItem(res.data)
+            }
+
             return {
                 type: 'success',
                 result: fullRes