[BUG] Allow TextClassification to generate text without structured generation

[plaguss]

Describe the bug
TextClassification only generates structured text, which can result on errors hard to get.

To Reproduce
Code to reproduce

Expected behaviour
Work as any other task

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Additional context
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[plaguss]

One can just pass the use_default_structured_output and use the default parser, the prompt would not change, and it should work if the model follows the instruction (but while testing, the results are almost always better using the structured output by default