appdata: Improve appdata for AppStream 1.0

- Add the `<developer><name>` tag
- Mark the `<developer_name>` tag as deprecated
- Use --no-net argument for appstreamcli to reduce traffic

data/com.github.huluti.Curtail.appdata.xml.in

@@ -11,7 +11,11 @@
     <p>Optimize your images with Curtail, a useful image compressor that supports PNG, JPEG, WebP and SVG file types.</p>
     <p>It supports both lossless and lossy compression modes with an option to whether keep or not metadata of images.</p>
   </description>
+  <!-- developer_name tag deprecated with Appstream 1.0 -->
   <developer_name translatable="no">Hugo Posnic</developer_name>
+  <developer id="github.com">
+    <name translatable="no">Hugo Posnic</name>
+  </developer>
   <update_contact>hugo.posnic@protonmail.com</update_contact>
   <url type="homepage">https://github.com/Huluti/Curtail</url>
   <url type="bugtracker">https://github.com/Huluti/Curtail/issues</url>
@@ -358,4 +362,3 @@
     </release>
   </releases>
 </component>
-

data/meson.build

@@ -36,7 +36,8 @@ appstream_file = i18n.merge_file(
 appstreamcli = find_program('appstreamcli', required: false)
 if appstreamcli.found()
   test('Validate appstream file', appstreamcli,
-    args: ['validate', appstream_file]
+    args: ['validate', '--no-net', '--explain', appstream_file],
+    workdir: meson.current_build_dir()
   )
 endif