Framework: Bump minimum required WP to 5.x (#13370)

gutenberg.php

@@ -146,7 +146,7 @@ function is_gutenberg_page() {
  */
 function gutenberg_wordpress_version_notice() {
 	echo '<div class="error"><p>';
-	_e( 'Gutenberg requires WordPress 4.9.8 or later to function properly. Please upgrade WordPress before activating Gutenberg.', 'gutenberg' );
+	_e( 'Gutenberg requires WordPress 5.0.0 or later to function properly. Please upgrade WordPress before activating Gutenberg.', 'gutenberg' );
 	echo '</p></div>';
 
 	deactivate_plugins( array( 'gutenberg/gutenberg.php' ) );
@@ -180,7 +180,7 @@ function gutenberg_pre_init() {
 	// Strip '-src' from the version string. Messes up version_compare().
 	$version = str_replace( '-src', '', $wp_version );
 
-	if ( version_compare( $version, '4.9.8', '<' ) ) {
+	if ( version_compare( $version, '5.0.0', '<' ) ) {
 		add_action( 'admin_notices', 'gutenberg_wordpress_version_notice' );
 		return;
 	}