fix(ci): install poetry before calling setup/python with cache

[rubenfonseca]

Issue number: #1009

Summary

Changes

Please provide a summary of what's being changed

This fixes a problem when Github actions that used poetry and dependency caching would fail, because poetry was not installed. Following the official documentation recomendation, we install poetry manually before the actions/setup-python action.

User experience

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Checklist

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• Meet tenets criteria
• I have performed a self-review of my this change
• Changes are tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

RFC issue number:

Checklist:

• Migration process documented
• Implement warnings (if it can live side by side)

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