Log Message:
neomutt: update to 20211022.

Remove slang option, because slang support was removed.

2021-10-22  Richard Russon  <rich@flatcap.org>
* Bug Fixes
  - fix new mail notifications
  - fix pattern compilation error for ~( !~>(~P) )
  - fix menu display on window resize
  - Stop batch mode emails with no argument or recipients
  - Add sanitize call in print mailcap function
  - fix `hdr_order` to use the longest match
  - fix (un)setenv to not return an error with unset env vars
  - fix Imap sync when closing a mailbox
  - fix segfault on OpenBSD current
  - sidebar: restore `sidebar_spoolfile` colour
  - fix assert when displaying a file from the browser
  - fix exec command in compose
  - fix `check_stats` for Notmuch mailboxes
  - Fallback: Open Notmuch database without config
  - fix gui hook commands on startup
* Changed Config
  - Re-enable `$ssl_force_tls`
* Translations
  - 100% Serbian
  - 100% Lithuanian
  - 100% German
* Build
  - Remove Slang from the build
  - Warn about deprecated configure options