dns/dnsmasq-devel: update to 2.91test6.

Also include one potential cache.c NULL deref which I have
submitted upstream.

Upstream Git log:

• 0003db1 2025-01-07 | Fix crash introduced in 6656790f2498f2a0b21086bc4ab47a2e38429a7c (tag: v2.91test6)
• 275f4a4 2025-01-07 | Remove arbitrary workspace size limit. (tag: v2.91test5)
• 12e4565 2025-01-06 | Improve "chown of PID file failed" message for missing CAP_CHOWN [Andrew Sayers]
• 7af26ee 2025-01-07 | Fix manpage typo. [Andrew Sayers]
• 63dc6eb 2025-01-07 | Fix read_write() changes for TCP timeout.
• 6656790 2025-01-07 | Handle queries with EDNS client subnet fields better.
• c8de423 2025-01-07 | Fix finger-trouble in immediately previous commit.
• c52653f 2025-01-06 | Correctly handle failure of pipe() call in swap_to_tcp()
• e24c341 2025-01-01 | Fix wrong packet size when dumpong packets to file.