Fix DNSdumpster CSRF extraction and add tests/CI

[mazennafee]

Summary

This PR fixes a crash when DNSdumpster omits its CSRF token by:

• Implementing a defensive get_csrftoken (regex + BeautifulSoup fallback).
• Delegating class method to the module-level function.
• Adding a unit test reproducing the missing-token case.
• Adding requirements.txt, LICENSE, and a GitHub Actions CI workflow.

Testing

1. python -m venv .venv && source .venv/bin/activate
2. pip install -r requirements.txt
3. pip install -e .
4. python -m pytest -q

Notes

Backwards compatible when DNSdumpster provides a token. Happy to split docs/CI/tests into separate PRs if preferred.
PR