Fix appstream stuff

org.kde.kalendar.appdata.xml

@@ -255,8 +255,8 @@
     <release type="development" version="0.4.0" date="2021-12-26">
       <description>
         <p>This release brings new views, improved performance, and significant bugfixes.</p>
-        <p>https://claudiocambra.com/2021/12/25/happy-holidays-kalendar-v0-4-0-is-our-gift-and-it-brings-new-views-improved-performance-and-many-many-bugfixes-kalendar-devlog-24/</p>
       </description>
+      <url>https://claudiocambra.com/2021/12/25/happy-holidays-kalendar-v0-4-0-is-our-gift-and-it-brings-new-views-improved-performance-and-many-many-bugfixes-kalendar-devlog-24/</url>
     </release>
     <release type="development" version="0.3.1" date="2021-12-02">
       <description>
@@ -266,8 +266,8 @@
     <release type="development" version="0.3.0" date="2021-11-30">
       <description>
         <p>This release brings an alarm client for reminders, major stability improvements, improved accessibility, visual tweaks, and more.</p>
-        <p>https://claudiocambra.com/2021/11/28/kalendar-v0-3-0-out-soon-with-improved-stability-efficiency-accessibility-and-a-windows-version-kalendar-devlog-23/</p>
       </description>
+      <url>https://claudiocambra.com/2021/11/28/kalendar-v0-3-0-out-soon-with-improved-stability-efficiency-accessibility-and-a-windows-version-kalendar-devlog-23/</url>
     </release>
     <release type="development" version="0.2.1" date="2021-11-15">
       <description>