[Bug] DeepSeek related environment not work

### 📦 Deployment Method

Docker

### 📌 Version

v2.15.8

### 💻 Operating System

Other Linux

### 📌 System Version

Alpine Linux 3.20

### 🌐 Browser

Chrome

### 📌 Browser Version

131.0.6778.205

### 🐛 Bug Description

I deployed nextweb via Docker Compose. I want the service to work by default through the deepseek model without relying on any configuration in the front-end page. This is my original compose file.
```
version: "3"
services:
chatgpt-web:
image: yidadaa/chatgpt-next-web:latest
restart: always
ports:
- "127.0.0.1:3000:3000"
environment:
- CODE=xxxxxx
- CUSTOM_MODELS=-all,+deepseek-chat@DeepSeek
- DEFAULT_MODEL=deepseek-chat
- DEEPSEEK_URL=https://api.deepseek.com
- DEEPSEEK_API_KEY=sk-xxxx
```
But it didn't work. seeing the logs, nextweb still request the apis of openai instead of deepseek.
Then I update my compose file like this, adding **OPENAI_API_KEY** and **BASE_URL** configs, pretend to request custom openai url with specified model *deepseek-chat*, and it works well.
```
version: "3"
services:
chatgpt-web:
image: yidadaa/chatgpt-next-web:latest
restart: always
ports:
- "127.0.0.1:3000:3000"
environment:
- OPENAI_API_KEY=sk-xxxx
- BASE_URL=https://api.deepseek.com
- CODE=xxxxxx
- CUSTOM_MODELS=-all,+deepseek-chat@DeepSeek
- DEFAULT_MODEL=deepseek-chat
- DEEPSEEK_URL=https://api.deepseek.com
- DEEPSEEK_API_KEY=sk-xxxx
```

I think there is something wrong with **DEEPSEEK_URL** and **DEEPSEEK_API_KEY** config items, or my misconfig, plz let me know the truth, thank you!

### 📷 Recurrence Steps

_No response_

### 🚦 Expected Behavior

_No response_

### 📝 Additional Information

_No response_