ci: standardise test matrix and update readme

Updates CI workflow to test against WP 6.4 and master with PHP 7.4 and
latest. Removes allowed_failure flag so CI fails if tests fail on any
supported configuration.

Updates plugin header PHP requirement from 5.6 to 7.4 to match
composer.json.

Adds standard plugin header fields to readme.txt including tested
versions (WP 6.9).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: GaryJones

.github/workflows/integration.yml

@@ -40,8 +40,13 @@ jobs:
 
     strategy:
       matrix:
-        wordpress: ['6.4', 'master']
-        php: ['7.4', '8.3']
+        include:
+          # Check lowest supported WP version, with the lowest supported PHP.
+          - wordpress: '6.4'
+            php: '7.4'
+          # Check latest WP with the latest PHP.
+          - wordpress: 'master'
+            php: 'latest'
       fail-fast: false
 
     steps:

media-explorer.php

@@ -4,7 +4,7 @@
 Description: Extends the Media Manager to add support for external media services (currently Twitter, YouTube, and Instagram).
 Version:     1.2
 Requires at least: 6.4
-Requires PHP: 5.6
+Requires PHP: 7.4
 Author:      Code For The People Ltd, Automattic
 Text Domain: mexp
 Domain Path: /languages/

readme.txt

@@ -1,7 +1,12 @@
 === Media Explorer ===
 Contributors: Automattic, johnbillion, garhdez, djpaul
 Tags: media, social media, twitter, youtube, media explorer
+Requires at least: 6.4
+Tested up to: 6.9
+Requires PHP: 7.4
 Stable tag: 1.2
+License: GPLv2 or later
+License URI: https://www.gnu.org/licenses/gpl-2.0.html
 
 Insert social media content into your posts.