dnscrypt-proxy2: Update to 2.0.31

* Version 2.0.31
- This version fixes two regressions introduced in version 2.0.29:
DoH server couldn't be reached over IPv6 any more, and the proxy
couldn't be interrupted while servers were being benchmarked.

* Version 2.0.30
- This version fixes a startup issue introduced in version 2.0.29,
on systems for which the service cannot be automatically installed
(such as OpenBSD and FreeBSD). Reported by @5ch17 and Vin鱈cius Zavam,
and fixed by Will Elwood, thanks!

* Version 2.0.29
- Support for Anonymized DNS has been added!
- Wait before stopping, fixing an issue with Unbound (thanks to
Vladimir Bauer)
- DNS stamps are now included in the -list-all -json ouptut
- The netprobe_timeout setting from the configuration file or
command-line was ignored. This has been fixed.
- The TTL or cloaked entries can now be adjusted (thanks to Markus
Linnala)
- Cached IP address from DoH servers now expire (thanks to Markus
Linnala)
- DNSCrypt certificates can be fetched over Tor and SOCKS proxies
- Retries over TCP are faster
- Improved logging (thanks to Alison Winters)
- Ignore non-TXT records in certificate responses (thanks to Vladimir
Bauer)
- A lot of internal cleanups, thanks to Markus Linnala.

(nia)