Extract python version from explicit main group (poetry)

[ticosax]

Description: Add support to detect python version from pyproject.toml file managed by poetry where the main group is using its fully qualified name. As documented here https://python-poetry.org/docs/managing-dependencies/#dependency-groups

[tool.poetry.dependencies]

and

[tool.poetry.group.main.dependencies]

Are equivalent

Related issue: N/A

Check list:

• [ ] Mark if documentation changes are required.
• [x] Mark if tests were added or updated to cover the changes.