[fix] engine - moviepilot instead of thumbnail use img_src

Instead of thumbnail use img_src in the result item, otherwise the "movies"
categories looks clunky.

Related:

- https://github.com/searxng/searxng/commit/b4e0d2eedc94df2369a7661f9134fcfd8fd68af4#r128785388

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/moviepilot.py

@@ -105,11 +105,11 @@ def response(resp):
             item['metadata'] = html_to_text(result.get('meta_short', ''))
 
             if result.get('image'):
-                item['thumbnail'] = image_url.format(image_id=result['image'], filename=result['image_filename'])
+                item['img_src'] = image_url.format(image_id=result['image'], filename=result['image_filename'])
         else:
             item['url'] = result['url']
             item['content'] = ', '.join([result['class'], result['info'], result['more']])
-            item['thumbnail'] = result['image']
+            item['img_src'] = result['image']
 
         results.append(item)