Fix trim(null) deprecation (#36)

Quick fix so it will work with PHP 8+
This is the cause of gantry/gantry5#3130

Author: osnodegeoffrey

Compat/src/Yaml/Inline.php

@@ -45,7 +45,7 @@ public static function parse($value, $exceptionOnInvalidType = false, $objectSup
         self::$objectSupport = $objectSupport;
         self::$objectForMap = $objectForMap;
 
-        $value = trim($value);
+        $value = trim($value ?? '');
 
         if ('' === $value) {
             return '';