Bump requests to >=2.33.0 (security) and release 1.0.12.1

[andrew-parkes]

Summary

• Raise the minimum requests version to >=2.33.0 for Python > 3.9 to resolve the Dependabot security advisories affecting requests < 2.33.0.
• Bump package version 1.0.12.0 → 1.0.12.1 (setup.py + PKG-INFO).
• Adjust environment markers so requests/urllib3 constraints apply to python_version > "3.9", and keep requests>=2.20.0 for the legacy 3.7–3.9 range (those interpreters can't install the patched requests).
• Simplify the test extra to a single pytest>=7.0,<10.0 constraint.

Notes

• The legacy Python 2.7 / 3.7–3.9 lines remain below the patched floor because requests>=2.33.0 dropped support for those interpreters; this preserves the library's documented Python 2.7+/3.6+ compatibility.
• Dependabot can't auto-apply this since setup.py uses version ranges rather than pinned versions, so the bump is applied manually here.