notmuch: Update to 0.32.1

Changelog:
Notmuch 0.32.1 (2021-05-15)
===========================

General
-------

Restore handling of relative values for `database.path` that was
broken by 0.32. Extend this handling to `database.mail_root`,
`database.backup_dir`, and `database.hook_dir`.

Reload certain metadata from Xapian database in
notmuch_database_reopen. This fixes a bug when adding messages to the
database in a pre-new hook.

Fix default of `$HOME/mail` for `database.path`. In release 0.32, this
default worked only in "notmuch config".

Emacs
-----

Restore the dynamically bound variables `tag-changes` and `query` in
in `notmuch-before-tag-hook` and `notmuch-after-tag-hook`.

(ryoon)