Release version 9.0.0

Author: meisterT

ChangeLog

@@ -1,6 +1,6 @@
 DOMjudge Programming Contest Judging System
 
-Version 9.0.0DEV
+Version 9.0.0 - 5 October 2025
 ---------------------------
  - API and integration:
    - Get rid of 'internal' data source mode, always requiring - but auto

README.md

@@ -6,7 +6,7 @@ DOMjudge
 [![Coverity Scan Status](https://img.shields.io/coverity/scan/671.svg)](https://scan.coverity.com/projects/domjudge)
 [![CodeQL alerts](https://github.com/DOMjudge/domjudge/actions/workflows/codeql-analysis.yml/badge.svg?branch=main&event=push)](https://github.com/DOMjudge/domjudge/actions/workflows/codeql-analysis.yml)
 
-This is the Programming Contest Jury System "DOMjudge" version 9.0.0DEV
+This is the Programming Contest Jury System "DOMjudge" version 9.0.0
 
 DOMjudge is a system for running a programming contest, like the
 ICPC regional and world championship programming contests.

SECURITY.md

@@ -5,9 +5,9 @@
 | DOMjudge Version | Supported          | PHP version supported |
 |------------------| ------------------ |-----------------------|
 | main branch      | :warning:          | 8.1-8.4               |
+| 8.4.x            | :white_check_mark: | 8.1-8.4               |
 | 8.3.x            | :white_check_mark: | 8.1-8.3               |
-| 8.2.x            | :white_check_mark: | 7.4-8.2               |
-| < 8.2            | :x:                | :x:                   |
+| < 8.3            | :x:                | :x:                   |
 
 ## Reporting a Vulnerability