Update WordPress tested version to 6.9

Co-authored-by: benbalter <282759+benbalter@users.noreply.github.com>

Author: Copilot

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     strategy: 
       matrix:
         php_version: [8.4]
-        wp_version: [latest, '6.7', '6.8']
+        wp_version: [latest, '6.7', '6.9']
         wp_multisite: [0]
         include:
           - php_version: 8.4

docs/header.md

@@ -2,7 +2,7 @@
 Contributors: benbalter
 Tags: jekyll, github, github pages, yaml, export, markdown
 Requires at least: 4.4
-Tested up to: 6.8
+Tested up to: 6.9
 Requires PHP: 7.2
 Stable tag: 2.4.2
 License: GPLv3 or later