Get rid of deprecated <developer_name> tag (by Marcos Fouces)

Fix deprecated tag use in termit.metainfo.xml

Author: nonstop

doc/termit.metainfo.xml

@@ -25,6 +25,8 @@
   <provides>
     <binary>termit</binary>
   </provides>
-  <developer_name>Evgeny Ratnikov</developer_name>
+  <developer>
+    <name>Evgeny Ratnikov</name>
+  </developer>
   <url type="bugtracker">https://github.com/nonstop/termit/issues</url>
 </component>