Update Artifact Lambda Unit Tests & Refactor for ruff

[Alrobbertz]

No description provided.

[Copilot]

Pull request overview

This PR updates the repository’s developer tooling and CI workflows to use Ruff, refreshes unit test mocking to align with newer Moto patterns, and migrates repository documentation from README.md to README.rst.

Changes:

• Update dev dependencies (pytest/moto) and replace Black/Flake8 with Ruff.
• Refactor unit tests to use Moto’s unified AWS mocking and introduce a pytest fixture.
• Modernize GitHub Actions workflows for testing, coverage upload, and Ruff-based lint/format.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
requirements.dev.txt	Updates test/dev dependencies and switches linting/formatting tooling to Ruff.
README.rst	Adds a new reStructuredText README with updated test/run instructions and badges.
README.md	Removes the previous Markdown README in favor of README.rst.
lambda_function/tests/test_process_artifacts.py	Updates Moto usage and refactors test setup to use a pytest fixture.
lambda_function/src/process_artifacts/process_artifacts.py	Ruff-oriented refactor: import ordering, typing, and updated docstrings.
lambda_function/src/lambda.py	Adds typing and refreshes handler documentation.
lambda_function/src/config.yaml	Removes the previously committed config file.
.github/workflows/testing.yml	Updates CI environment/actions and adds Codecov upload step.
.github/workflows/codestyle.yml	Replaces Black/Flake8 workflow with Ruff-based lint/format.
.github/workflows/build_and_push.yml	Removes the prior self-hosted Docker build/push workflow.

Comments suppressed due to low confidence (1)

requirements.dev.txt:8

• All other dev tools here are version-pinned, but ruff is left unpinned. This can make CI results non-reproducible when Ruff releases new rules/formatting. Consider pinning Ruff to a known-good version.

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