get sonatype releases working again

[dwrensha]

I wanted to make a new release on Maven Central to include the recent fix b830a0a. But I ended up punting: e63801c

But my local credentials for making a release have been invalidated. It looks like I might need to re-register and to add a DNS TXT record to capnproto.org. See https://central.sonatype.org/register/legacy/

From March 12th, 2024, all registration will be via the Central Portal. This page is intended primarily for users who need to publish with legacy OSSRH.