appdata: Remove none OARS tags

"The old generator also included all the none-value entries—it
no longer does this, you can safely remove them.

If it only consists of none values, it’s safe to shorten it to just:
`<content_rating type="oars-1.1" />`"

More information: https://docs.flathub.org/docs/for-app-authors/appdata-guidelines/#oars-information

data/org.gnome.Mines.appdata.xml.in

@@ -46,28 +46,7 @@
   </kudos>
   <translation type="gettext">gnome-mines</translation>
   <developer_name>Robert Roth</developer_name>
-  <!-- Generated by  http://apps-xdgapp.rhcloud.com/oars --> 
-  <content_rating type="oars-1.0">
-    <content_attribute id="violence-cartoon">none</content_attribute>
-    <content_attribute id="violence-fantasy">none</content_attribute>
-    <content_attribute id="violence-realistic">none</content_attribute>
-    <content_attribute id="violence-bloodshed">none</content_attribute>
-    <content_attribute id="violence-sexual">none</content_attribute>
-    <content_attribute id="drugs-alcohol">none</content_attribute>
-    <content_attribute id="drugs-narcotics">none</content_attribute>
-    <content_attribute id="drugs-tobacco">none</content_attribute>
-    <content_attribute id="sex-nudity">none</content_attribute>
-    <content_attribute id="sex-themes">none</content_attribute>
-    <content_attribute id="language-profanity">none</content_attribute>
-    <content_attribute id="language-humor">none</content_attribute>
-    <content_attribute id="language-discrimination">none</content_attribute>
-    <content_attribute id="social-chat">none</content_attribute>
-    <content_attribute id="social-info">none</content_attribute>
-    <content_attribute id="social-audio">none</content_attribute>
-    <content_attribute id="social-location">none</content_attribute>
-    <content_attribute id="social-contacts">none</content_attribute>
-    <content_attribute id="money-purchasing">none</content_attribute>
-    <content_attribute id="money-gambling">none</content_attribute>
-  </content_rating>
+  <!-- Generated by  http://apps-xdgapp.rhcloud.com/oars -->
+  <content_rating type="oars-1.1" />
 
 </component>