Update appcast.xml

Author: intitni

appcast.xml

@@ -2,6 +2,19 @@
 <rss xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/sparkle" version="2.0">
   <channel>
     <title>Copilot for Xcode</title>
+
+    <item>
+      <title>0.15.3</title>
+      <pubDate>Mon, 15 May 2023 18:46:47 +0800</pubDate>
+      <sparkle:version>153</sparkle:version>
+      <sparkle:shortVersionString>0.15.3</sparkle:shortVersionString>
+      <sparkle:minimumSystemVersion>12.0</sparkle:minimumSystemVersion>
+      <sparkle:releaseNotesLink>
+        https://github.com/intitni/CopilotForXcode/releases/tag/0.15.3
+      </sparkle:releaseNotesLink>
+      <enclosure url="https://github.com/intitni/CopilotForXcode/releases/download/0.15.3/Copilot.for.Xcode.app.zip" length="21342371" type="application/octet-stream" sparkle:edSignature="YYOBKinz8Ay++VYFIOwFRi4xcM3WuOTmPG6n4ar8e7Nc8Sq/JPLWaR2b6wLU05No2DCzMxlHXCF+a4a+o5V4AQ=="/>
+    </item>
+
     <item>
       <title>0.15.2</title>
       <pubDate>Sun, 14 May 2023 20:58:20 +0800</pubDate>