[python] Drop poetry v1 support

[stephenfin]

This is a collection of individual changes that collectively bump the minimum version of poetry to v2, remove stuff that was only applicable for older versions, and migrates things from flake8 to ruff. This PR is likely easier to review on a commit-by-commit basis: I've tried to provide as much detail as possible about what I've done and why I did it in each commit, and the whole thing should be fully bisectable.

• [python] Re-generate samples
• [python] Drop fallback for poetry 1.x
• [python] Switch build backend to poetry-core
• [python] Remove setup.py file
• [python] Migrate from flake8 to ruff
• [python] Stop generating requirements.txt files by default

CC: @cbornet @tomplus @krjakbrjak @fa0311 @multani

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

---

Summary by cubic

Drops Poetry v1 support and switches Python outputs to Poetry 2 with poetry-core, replacing setuptools scaffolding. Also migrates linting to Ruff and stops generating requirements.txt by default; samples and docs updated.

• Refactors

  • Require Poetry 2; set build-backend to poetry-core (PEP 517/621).
  • Remove setup.py/setup.cfg and related README instructions.
  • Migrate from flake8 to ruff; update test deps.
  • Generate requirements.txt and test-requirements.txt only when generateSourceCodeOnly is enabled; otherwise rely on pyproject.toml.
  • Update CLI help to reference project name in pyproject.toml.
  • Regenerate Python samples; drop legacy files (requirements.txt, setup.* , poetry.lock) and stale docs/tests.

• Migration

  • Use Poetry 2+ (poetry-core) for builds: pyproject.toml is the single source of truth.
  • Replace flake8 lint steps with ruff (ruff check/ruff format).
  • If you depended on setup.py/setup.cfg, move to pyproject.toml.
  • If you need requirements files, use source-only generation or create them from pyproject.

^{Written for commit 8b45bf1. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 97 files

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="modules/openapi-generator/src/main/resources/python/README_onlypackage.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/python/README_onlypackage.mustache:27">
P2: Typo: `requirement.txt` should be `requirements.txt` (missing 's'). This inconsistency would confuse users trying to follow the installation instructions.</violation>
</file>

---

Since this is your first cubic review, here's how it works:

• cubic automatically reviews your code and comments on bugs and improvements
• Teach cubic by replying to its comments. cubic learns from your replies and gets better over time
• Ask questions if you need clarification on any suggestion

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}