appdata: Improve appdata for AppStream 1.0

- Add the `<developer><name>` tag
- Mark the `<developer_name>` tag as deprecated
- Improve appstreamcli arguments

data/com.github.maoschanz.drawing.appdata.xml.in

@@ -157,7 +157,11 @@
     </release>
   </releases>
 
+  <!-- developer_name tag deprecated with Appstream 1.0 -->
   <developer_name translatable="no">Romain F. T.</developer_name>
+  <developer id="github.com">
+    <name translatable="no">Romain F. T.</name>
+  </developer>
   <update_contact>[email protected]</update_contact>
   <url type="homepage">https://maoschanz.github.io/drawing</url>
   <url type="bugtracker">https://github.com/maoschanz/drawing/issues</url>

data/meson.build

@@ -43,7 +43,8 @@ if get_option('enable-translations-and-appdata')
 		test(
 			'Validate appstream file',
 			appstreamcli,
-			args: ['validate', '--no-net', appstream_file]
+			args: ['validate', '--no-net', '--explain', appstream_file],
+			workdir: meson.current_build_dir()
 		)
 	endif
 endif