feat: Support Poetry v2 requires-poetry version constraint

[markhallen]

What are you trying to accomplish?

Poetry v2 introduced a requires-poetry field in pyproject.toml that allows projects to declare which Poetry versions are compatible. When Dependabot encounters a project with this constraint and the detected Poetry version doesn't satisfy it, the update should fail early with a clear ToolVersionNotSupported error rather than producing confusing failures downstream.

This follows the same pattern used by npm_and_yarn for engines constraints.

Anything you want to highlight for special attention from reviewers?

• The requires_poetry_version_constraint method in file_parser.rb parses the tool.poetry.requires-poetry field from pyproject.toml using TomlRB and wraps it in a Dependabot::Python::Requirement. It returns nil gracefully on parse errors or missing fields.
• The PoetryPackageManager#raise_if_unsupported! override calls super first (for existing deprecated/unsupported version checks), then checks the project's declared constraint against the detected version using requirement.satisfied_by?(version).
• The validation is wired through the existing dependency_snapshot.rb → ecosystem.raise_if_unsupported! → package_manager.raise_if_unsupported! pipeline — no changes to common/base classes were needed.

How will you know you've accomplished your goal?

• 14 new tests added and all passing:
  • 7 tests in poetry_package_manager_spec.rb covering #raise_if_unsupported! with no requirement, satisfied requirement, unsatisfied requirement (with error attribute checks), and multi-constraint ranges (within/above/below).
  • 4 tests in file_parser_spec.rb covering integration: satisfied constraint, unsatisfied constraint (raises via ecosystem.raise_if_unsupported!), complex multi-part constraints, and absent field.
  • 3 fixture files: requires_poetry_satisfied.toml, requires_poetry_not_satisfied.toml, requires_poetry_complex.toml.
• RuboCop passes on all changed files with no offenses.

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[Copilot]

Pull request overview

Adds early, user-friendly failure when a project’s pyproject.toml declares a Poetry requires-poetry constraint that isn’t satisfied by the detected Poetry version, by surfacing ToolVersionNotSupported instead of failing later in the update pipeline.

Changes:

• Parse tool.poetry.requires-poetry from pyproject.toml and attach it as a Dependabot::Python::Requirement to the detected Poetry package manager.
• Enforce the constraint in PoetryPackageManager#raise_if_unsupported! by raising Dependabot::ToolVersionNotSupported when unsatisfied.
• Add fixtures and specs covering satisfied/unsatisfied and multi-part constraints.

Show a summary per file

File	Description
python/lib/dependabot/python/file_parser.rb	Parses requires-poetry from pyproject.toml and passes it into PoetryPackageManager during detection.
python/lib/dependabot/python/package_manager.rb	Adds constraint enforcement in PoetryPackageManager#raise_if_unsupported!.
python/spec/dependabot/python/file_parser_spec.rb	Integration tests verifying constraint parsing and enforcement via ecosystem.raise_if_unsupported!.
python/spec/dependabot/python/poetry_package_manager_spec.rb	Unit tests for requirement storage and #raise_if_unsupported! behavior.
python/spec/fixtures/pyproject_files/requires_poetry_satisfied.toml	Fixture with a satisfied requires-poetry constraint.
python/spec/fixtures/pyproject_files/requires_poetry_not_satisfied.toml	Fixture with an unsatisfied requires-poetry constraint.
python/spec/fixtures/pyproject_files/requires_poetry_complex.toml	Fixture with a multi-part requires-poetry constraint.

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 1