add the 7.1 release to the metainfo file

Author: fabiangreffrath

src/Doom.metainfo.xml.in

@@ -64,6 +64,7 @@
     <content_attribute id="social-chat">intense</content_attribute>
   </content_rating>
   <releases>
+    <release version="7.1" date="2025-09-23"/>
     <release version="7.0" date="2024-08-09"/>
     <release version="6.0" date="2023-03-31"/>
     <release version="5.12.0" date="2022-09-01"/>