Fix nbsp handling in Markdown encoder

Author: petercv

src/MarkupKit/Core/String/Encoder/Markdown/MarkdownEncoder.php

@@ -54,7 +54,8 @@ protected function encodeElement(AbstractAttributedElement $element): string
      */
     private function splitTrailingWhitespace(string $text): array
     {
-        if (preg_match('/\s+$/', $text, $matches)) {
+        // use unicode-aware regex to match trailing whitespace including non-breaking spaces
+        if (preg_match('/\s+$/u', $text, $matches)) {
             $trailingSpaces = $matches[0];
             return [substr($text, 0, -strlen($trailingSpaces)), $trailingSpaces];
         }

tests/MarkdownEncoderTest.php

@@ -48,6 +48,7 @@ public static function encodingDataProvider(): array
             ['<img src="image.jpg" alt="Image" title="Title">', '![Image](image.jpg "Title")'],
             ['<img src="image.jpg" alt="">', '![image](image.jpg)'],
             ['<img src="image.jpg">', '![image](image.jpg)'],
+            ['<b>More: </b>you can find more information here', '**More:** you can find more information here']
         ];
 
         return array_combine(