epub converter: fix <pre> 3

src/html_epub_preprocessor.py

@@ -404,7 +404,7 @@ def preprocess_pre_tags(chapter_tag):
 
         for child in pre.children:
             if isinstance(child, NavigableString):
-                text = escape(pre.text)
+                text = pre.text
                 text = text.replace('\t', '      ')
                 text = text.replace(' ', '  ')
                 elements = re.split('\r\n|\n|\r', text)