Improve regex to handle code snippets "<" when using the syntax highl…

…ighter block

syntaxhighlighter.php

@@ -554,7 +554,7 @@ public function render_block( $attributes, $content ) {
 			}
 		}
 
-		$code = preg_replace( '#<pre [^>]+>([^<]+)?</pre>#', '$1', $content );
+		$code = preg_replace( '#<pre [^>]+>(.*)</pre>#s', '$1', $content );
 
 		// Undo escaping done by WordPress
 		$code = htmlspecialchars_decode( $code );