dns/powerdns: update to 4.8.1

ChangeLog: https://blog.powerdns.com/2023/07/07/authoritative-server-4-8-1

New Features

• lmdb: add backend commands for checking & refreshing indexes

Improvements

• lmdb: in Lightning Stream mode, during deleteDomain, use RW transaction to get ID list
• Stop using the now deprecated ERR_load_CRYPTO_strings() to detect OpenSSL
• Work around Red Hat 8 pooping the bed in OpenSSL’s headers

Bug Fixes

• YaHTTP: Prevent integer overflow on very large chunks

PR: 272476
Reported by: tremere@cainites.net (maintainer)