Fix python_version operators in PyPI dependency marker parsing

[Pradeepbeleri]

Fixes #5309

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated CHANGELOG.rst (if applicable)

Description

Fixes issue #5309 in get_python_version_os() inside src/packagedcode/pypi.py where python_version_operators contained a duplicate '<' entry and was missing comparison operators '>', '!=', and '~='.

Because those operators were missing, dependency markers like python_version > "3.8" or python_version != "3.6" were silently dropping their python_version extra data during PyPI package scanning.

Changes Made

• Updated python_version_operators in src/packagedcode/pypi.py to ['<', '>', '>=', '==', '<=', '!=', '~='].
• Added author entry in AUTHORS.rst.
• Added entry in CHANGELOG.rst.

Verification

• Executed full PyPI test suite (python -m pytest tests/packagedcode/test_pypi.py): 184 passed.