🐞 GitLab SelfHosted: Can't add account

### Description

Hi there,

I'm not able to add the GitLab Self Hosted account, in the terminal there is this warning

`git auth failure: dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "Unexpected character '<' around line 1, column 1." UserInfo={NSDebugDescription=Unexpected character '<' around line 1, column 1., NSJSONSerializationErrorIndex=0})))
`

### To Reproduce

1. Go to Settings;
2. Navigate to Account;
3. Click on Add account;
4. Select GitLab SelfHosted
5. Insert as host: https://git.offertetou********.com/
6. Insert My User name (andrea.calabro at offertetou********.com)
7. Insert My Personal Token;
8. Click on Sign In
9. Error

### Expected Behavior

Login to my Self hosted GitLab

### Version Information

CodeEdit: Version 0.1.0-alpha (38)
macOS: 14.5 (23F79)

### Additional Context

_No response_

### Screenshots

从 GitLab SelfHosted 的 Settings > Account > Add account 流程开始，使用 self-hosted 主机、用户名和个人令牌重现报告中的登录问题。检查终端解码警告以及身份验证期间返回的响应；完成的标准是能够成功添加有效的 self-hosted GitLab 账户，而不是产生 JSON 解码错误。

由索引模型根据 Issue 内容生成。