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/com.github.geigi.cozy.appdata.xml

@@ -220,37 +220,8 @@
       </description>
     </release>
   </releases>
-
-  <content_rating type="oars-1.1">
-    <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="violence-desecration">none</content_attribute>
-    <content_attribute id="violence-slavery">none</content_attribute>
-    <content_attribute id="violence-worship">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="sex-homosexuality">none</content_attribute>
-    <content_attribute id="sex-prostitution">none</content_attribute>
-    <content_attribute id="sex-adultery">none</content_attribute>
-    <content_attribute id="sex-appearance">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>
-
+
+  <content_rating type="oars-1.1" />
   <custom>
     <value key="x-appcenter-color-primary">#FB6542</value>
     <value key="x-appcenter-color-primary-text">#FFFFFF</value>