Bump Tested up to 6.9 and align Requires PHP at 7.4

- Tested up to: 6.6 → 6.9 in both readme.txt and the plugin header.
- Requires PHP: align both files at 7.4. readme.txt previously declared
  7.2 while wp-job-manager.php declared 7.4 — WordPress.org reads the
  readme value, so the effective floor was 7.2, but the CI matrix only
  tests 7.4+. Standardising on 7.4 (already the de-facto tested floor).

Author: donnchawp

readme.txt

@@ -2,8 +2,8 @@
 Contributors: mikejolley, automattic, adamkheckler, alexsanford1, annezazu, cena, chaselivingston, csonnek, davor.altman, donnapep, donncha, drawmyface, erania-pinnera, fjorgemota, jacobshere, jakeom, jeherve, jenhooks, jgs, jonryan, kraftbj, lamdayap, lschuyler, macmanx, nancythanki, orangesareorange, rachelsquirrel, renathoc, ryancowles, richardmtl, scarstocea
 Tags: jobs, careers, company, hiring, job board
 Requires at least: 6.4
-Tested up to: 6.6
-Requires PHP: 7.2
+Tested up to: 6.9
+Requires PHP: 7.4
 Stable tag: 2.4.2
 License: GPLv3
 License URI: http://www.gnu.org/licenses/gpl-3.0.html

wp-job-manager.php

@@ -7,7 +7,7 @@
  * Author: Automattic
  * Author URI: https://wpjobmanager.com/
  * Requires at least: 6.4
- * Tested up to: 6.6
+ * Tested up to: 6.9
  * Requires PHP: 7.4
  * Text Domain: wp-job-manager
  * Domain Path: /languages/