Prepare for next release

Add a CHANGES.md for user-visible changes. Bump the plugin version and
release version.

Author: dlmsr

CHANGES.md

@@ -0,0 +1,8 @@
+CHANGELOG
+=========
+
+Changes in v5.0-r1 (since v4.5-r1)
+----------------------------------
+
+- support for Moodle 5.0
+- add CHANGES.md for user-visible changes

version.php

@@ -24,8 +24,8 @@
 defined('MOODLE_INTERNAL') || die();
 
 
-$plugin->version   = 2025021900;     // The current plugin version (Date: YYYYMMDDXX).
+$plugin->version   = 2025091700;     // The current plugin version (Date: YYYYMMDDXX).
 $plugin->requires  = 2022112800;     // Requires 4.1+ Moodle version.
 $plugin->component = 'block_groups'; // Full name of the plugin (used for diagnostics).
-$plugin->release = 'v4.5-r1';
+$plugin->release = 'v5.0-r1';
 $plugin->maturity = MATURITY_STABLE;