Update admin_manual/installation/system_requirements.rst

Co-authored-by: Côme Chilliet <91878298+come-nc@users.noreply.github.com>
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

admin_manual/installation/system_requirements.rst

@@ -25,7 +25,7 @@ For best performance, stability and functionality we have documented some recomm
 +------------------+-----------------------------------------------------------------------+
 | Database         | - **MySQL 8.0+** or MariaDB 10.3/10.5/**10.6** (recommended)/10.11    |
 |                  | - Oracle Database 11g (*only as part of an enterprise subscription*)  |
-|                  | - PostgreSQL 12/13/14/15/16                                           |
+|                  | - PostgreSQL 12/13/14/15                                              |
 |                  | - SQLite (*only recommended for testing and minimal-instances*)       |
 +------------------+-----------------------------------------------------------------------+
 | Webserver        | - **Apache 2.4 with** ``mod_php`` **or** ``php-fpm`` (recommended)    |