Fix doc_build CI failure after tox 4.36.0 upgrade

[Copilot]

Tox 4.36.0 introduced stricter validation for package extras, causing doc_build CI to fail with "extras not found for package bandersnatch: doc-build".

Changes

• Removed invalid extras = doc_build reference from [testenv:doc_build] in tox.ini
• The extra was never defined in setup.cfg (only s3, safety_db, and uvloop exist)
• Dependencies remain correctly specified via deps = -r requirements_docs.txt

[testenv:doc_build]
basepython=python3
commands = ...
deps = -r requirements_docs.txt
-extras = doc_build  # Removed - non-existent extra
passenv = SSH_AUTH_SOCK

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• docs.python.org
  • Triggering command: /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/sphinx-build -a -W --keep-going -b html docs docs/html (dns block)
• packaging.pypa.io
  • Triggering command: /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/sphinx-build -a -W --keep-going -b html docs docs/html (dns block)
• py-filelock.readthedocs.io
  • Triggering command: /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/python /home/REDACTED/work/bandersnatch/bandersnatch/.tox/doc_build/bin/sphinx-build -a -W --keep-going -b html docs docs/html (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)