[fix] bing news results return invalid images

Closes: https://github.com/searxng/searxng/issues/3502
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/bing_news.py

@@ -123,7 +123,9 @@ def response(resp):
         thumbnail = None
         imagelink = eval_xpath_getindex(newsitem, './/a[@class="imagelink"]//img', 0, None)
         if imagelink is not None:
-            thumbnail = 'https://www.bing.com/' + imagelink.attrib.get('src')
+            thumbnail = imagelink.attrib.get('src')
+            if not thumbnail.startswith("https://www.bing.com"):
+                thumbnail = 'https://www.bing.com/' + thumbnail
 
         results.append(
             {