Merge pull request #2257 from Solirs/fix_bad_escape

re.escape() the query in highlight_content to prevent a server side error.

searx/webutils.py

@@ -174,7 +174,9 @@ def highlight_content(content, query):
             queries.extend(re.findall(regex_highlight_cjk(qs), content, flags=re.I | re.U))
     if len(queries) > 0:
         for q in set(queries):
-            content = re.sub(regex_highlight_cjk(q), f'<span class="highlight">{q}</span>', content)
+            content = re.sub(
+                regex_highlight_cjk(q), f'<span class="highlight">{q}</span>'.replace('\\', r'\\'), content
+            )
     return content