Update appcast.xml

Author: intitni

appcast.xml

@@ -4,15 +4,15 @@
     <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>
+      <title>0.15.4</title>
+      <pubDate>Mon, 15 May 2023 22:13:11 +0800</pubDate>
+      <sparkle:version>154</sparkle:version>
+      <sparkle:shortVersionString>0.15.4</sparkle:shortVersionString>
       <sparkle:minimumSystemVersion>12.0</sparkle:minimumSystemVersion>
       <sparkle:releaseNotesLink>
-        https://github.com/intitni/CopilotForXcode/releases/tag/0.15.3
+        https://github.com/intitni/CopilotForXcode/releases/tag/0.15.4
       </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=="/>
+      <enclosure url="https://github.com/intitni/CopilotForXcode/releases/download/0.15.4/Copilot.for.Xcode.app.zip" length="21344856" type="application/octet-stream" sparkle:edSignature="p72+LRQrBfOvNig7bQaYXSun0KKmjQ982LsmZpR/Z4QSwWJWHqyzIx4lWBWmiikhjwgR6Bu9jWB4eWtJjJQsDQ=="/>
     </item>
 
     <item>