Merge #1694

1694: update compression algorithms for current dovecot r=nextgens a=lub

## What type of PR?

enhancement

## What does this PR do?

This adds additional compression algorithms in accordance with
https://doc.dovecot.org/configuration_manual/zlib_plugin/

### Related issue(s)

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


Co-authored-by: lub <git@lubiland.de>

core/dovecot/conf/dovecot.conf

@@ -21,7 +21,10 @@ mail_access_groups = mail
 maildir_stat_dirs = yes
 mailbox_list_index = yes
 mail_vsize_bg_after_count = 100
-mail_plugins = $mail_plugins quota quota_clone zlib{{ ' ' }}
+mail_plugins = $mail_plugins quota quota_clone{{ ' ' }}
+  {%- if COMPRESSION -%}
+  zlib{{ ' ' }}
+  {%- endif %}
   {%- if (FULL_TEXT_SEARCH or '').lower() not in ['off', 'false', '0'] -%}
   fts fts_xapian
   {%- endif %}
@@ -50,7 +53,7 @@ plugin {
   fts_autoindex_exclude = \Trash
   {% endif %}
 
-  {% if COMPRESSION in [ 'gz', 'bz2' ] %}
+  {% if COMPRESSION in [ 'gz', 'bz2', 'lz4', 'zstd' ] %}
   zlib_save = {{ COMPRESSION }}
   {% endif %}