[Bug] fix: error when parse complex content in completion body

[firebook]

Pull Request Description

AiBrix will raise an error when parse complex content in completion body

error message:

/v1/chat/completions json unmarhsal valid messages with complex content%!(EXTRA string=/v1/chat/completions json unmarhsal valid messages with complex content)

request body:

{"model": "llama2-7b", "messages": [{"role": "system", "content": "this is system"},{"role": "user", "content": [{"type": "text", "text": "say this is test"}, {"type": "text", "text": "say this is test"}]}]}

Related Issues

Resolves: #[Insert issue number(s)]

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[varungup90]

Can add one e2e test for content array.