There is an updated pull request by congdanhqx against master on the void-packages repository

https://github.com/congdanhqx/void-packages notmuch-0.28.4
https://github.com/void-linux/void-packages/pull/11528

notmuch: update to 0.28.4.
While we're at it, correct dependencies of notmuch-python:
it should depend on libnotmuch instead of libnotmuch-devel

A patch file from https://github.com/void-linux/void-packages/pull/11528.patch is attached