PHP: Bump the recommended version of PHP to 7.4.

This brings the recommendations in `readme.html` inline with those on https://wordpress.org/about/requirements/.

Props hareesh-pillai.
Fixes #50480.
Built from https://develop.svn.wordpress.org/trunk@48178


git-svn-id: http://core.svn.wordpress.org/trunk@47947 1a063a9b-81f0-0310-95a4-ce76da25c4cd

readme.html

@@ -57,7 +57,7 @@
 
 <h3>Recommendations</h3>
 <ul>
-	<li><a href="https://secure.php.net/">PHP</a> version <strong>7.3</strong> or higher.</li>
+	<li><a href="https://secure.php.net/">PHP</a> version <strong>7.4</strong> or higher.</li>
 	<li><a href="https://www.mysql.com/">MySQL</a> version <strong>5.6</strong> or higher.</li>
 	<li>The <a href="https://httpd.apache.org/docs/2.2/mod/mod_rewrite.html">mod_rewrite</a> Apache module.</li>
 	<li><a href="https://wordpress.org/news/2016/12/moving-toward-ssl/">HTTPS</a> support.</li>

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48177';
+$wp_version = '5.5-alpha-48178';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.