docs: for new installs, pin postgres container to debian trixie to avoid collation version mismatch (teslamate-org#4901)

* cast final result to smallint

* Revert "cast final result to smallint"

This reverts commit f80b62f.

* for new installs, pin postgres container to debian trixie

* docs: update changelog

---------

Co-authored-by: Jakob Lichterfeld <jakob-lichterfeld@gmx.de>

Author: swiffer

CHANGELOG.md

@@ -16,6 +16,8 @@
 
 #### Documentation
 
+- docs: for new installs, pin postgres container to debian trixie to avoid collation version mismatch (#4901 - @swiffer)
+
 ## [2.1.1] - 2025-08-16
 
 As always, there have been many improvements. We now use the latest version of Grafana (12.1.1) and have enhanced the database migration process to include the new ascent and descent values, allowing successful migration even when entries are faulty. Previously, this prevented the migration from succeeding for some users. This highlights the importance of user feedback. Such cases never occurred in our testing.

website/docs/installation/docker.md

@@ -40,7 +40,7 @@ Alternatively, you can use a reverse proxy (such as Traefik, Apache2 or Caddy) w
          - all
 
      database:
-       image: postgres:17
+       image: postgres:17-trixie
        restart: always
        environment:
          - POSTGRES_USER=teslamate

website/docs/maintenance/upgrading_postgres.md

@@ -20,7 +20,7 @@ sidebar_label: Upgrading PostgreSQL
 
    ```yml {2}
    database:
-     image: postgres:xx
+     image: postgres:xx-trixie
    ```
 
    ```bash