[FEATURE] Add MiniMax to the provider enum

[inference-gateway-maintainer]

Summary

inference-gateway/schemas added MiniMax to the provider enum in openapi.yaml (inference-gateway/schemas#62, which closes inference-gateway/schemas#61). This Python SDK is generated from schemas, so it must be regenerated to expose the new minimax provider value to consumers.

MiniMax is an OpenAI-compatible provider (id minimax, bearer auth, base URL https://api.minimax.io/v1, supports_vision: true).

Acceptance Criteria

• Regenerate the SDK models from the updated schemas openapi.yaml.
• minimax is present in the generated provider enum.
• Package builds and type-checks pass, and the change is released per the repo's normal flow.

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Source: inference-gateway/schemas#62 (closes inference-gateway/schemas#61)