Updated screenshot url

Author: leolost2605

data/io.github.leolost2605.gradebook.metainfo.xml

@@ -24,7 +24,7 @@
     </screenshot>
     <screenshot>
       <caption>Example for a subject with its grades</caption>
-      <image>https://raw.githubusercontent.com/leolost2605/Gradebook/1fbefa95eb502e44567d82b6db146e1fb9c0e3e8/data/subject.png</image>
+      <image>https://raw.githubusercontent.com/leolost2605/Gradebook/b4e4053b1afc01835b61a70158902eb03cca4a70/data/subject.png</image>
     </screenshot>
   </screenshots>