MDL-76722 core: Fix upgrade failures with MariaDB

The 'enable' field doesn't exist, and this is causing some failures
with MariaDB (and probably with MySQL too).

lib/db/upgrade.php

@@ -3218,7 +3218,7 @@ privatefiles,moodle|/user/files.php';
     if ($oldversion < 2023041100.00) {
         // Add public key field to user_devices table.
         $table = new xmldb_table('user_devices');
-        $field = new xmldb_field('publickey', XMLDB_TYPE_TEXT, null, null, null, null, null, 'enable');
+        $field = new xmldb_field('publickey', XMLDB_TYPE_TEXT, null, null, null, null, null, 'uuid');
 
         if (!$dbman->field_exists($table, $field)) {
             $dbman->add_field($table, $field);