ci: drop redundant Python test workflow dependencies

[kieran-ryan]

🤔 What's changed?

• Dropped pip, setuptools, twine, wheel installations before 'Run tests' step in test workflow
• Ignored *.egg-info/ build artefact in .gitignore
• Switched to long option names such as --requirement and --editable

⚡️ What's your motivation?

• Streamline the test workflow by removing redundant installations
  • setuptools and wheel are specified as build dependencies in the pyproject.toml file and thus will install on build commands - such as pip install . or python -m build - without explicitly installing them directly [See Remove explicit installation of setuptools nodejs/gyp-next#278]
  • pip install pip will only keep the same version - though pip install --upgrade pip would update pip if a later version was available
  • twine usage has been dropped from the Run tests step and migrated to the Build package step where it is additionally installed
• Ensure build artifacts are not committed to version control
• Long option names may be more intuitive for contributors less familiar with Python in a polyglot repo [see Anthony Sottile's take]

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, etc. without changing behaviour)

♻️ Anything particular you want feedback on?

• Intended to switch from a development (or editable) -e installation to a standard installation to ensure we test against a clean build - though retaining as only suffices to install test dependencies at present - as we do not test against a clean package build - see python: Test against build package #322. To be resolved in a separate pull request.

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct