AXFRDDNS: Add missing ALPN token 'dot'

[Mr-Foo]

AXFRDDNS does not comply with RFC 9103 "DNS Zone Transfer over TLS " section 7.1 "Connection Establishment", which states:

During connection establishment, the Application-Layer Protocol
Negotiation (ALPN) token "dot" [DoT-ALPN] MUST be selected in the TLS
handshake. [1]

Without ALPN bind (tested 9.20.22) refuses to return the zone:

(16.172.in-addr.arpa): view default: query failed (no ALPN) for 16.172.in-addr.arpa/IN/AXFR at query.c:12143

While dnscontrol logs:

INFO#1: Domain "16.172.in-addr.arpa" provider axfrddns Error: [Error] AXFRDDNS: nameserver refused to transfer the zone 16.172.in-addr.arpa: dns: bad xfr rcode: 2

Since the requirement in RFC 9103 is strict, I propose to unconditionally add NextProtos: dot.

[1] RFC 9103

[Mr-Foo]

@hnrgrgr please review.

[TomOnTime]

Thank you for sending this!

Right now the project is in transition but I hope to be able to address this once we've moved to our new git org.

[Mr-Foo]

Thank you for your consideration.

I will be happy to revisit this PR once you are ready.

[TomOnTime]

CC @hnrgrgr for confirmation