chore: remove duplicate v1.3.1 appcast entry

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Bengerthelorf

IconChanger/Resources/sparkle.xml

@@ -13,16 +13,6 @@
             sparkle:edSignature="jWrQZ31taNYXeKd9Z5qZEL4aRVJz5CVijyILZNjYfIzr/YypinLrl08OtkryShx7/kZ/E7mGmHr1kjucUxigCA==" length="10669863"
             type="application/octet-stream"/>
         </item>
-        <item>
-            <title>Version 1.3.1</title>
-            <link>https://github.com/Bengerthelorf/macIconChanger</link>
-            <sparkle:version>131</sparkle:version>
-            <sparkle:shortVersionString>1.3.1</sparkle:shortVersionString>
-            <pubDate>Fri, 06 Mar 2026 23:29:14 +0000</pubDate>
-            <enclosure url="https://github.com/Bengerthelorf/macIconChanger/releases/download/v1.3.1/IconChanger.dmg"
-            sparkle:edSignature="yWzA7wpknrI7G2VvMViton5dSkOWTtckpX1/NCWA/lcZImtKuPA6+0fOSwkQ5Jx6oHxUUAVCgqk1xWTcZ6BjDg==" length="9477510"
-            type="application/octet-stream"/>
-        </item>
         <item>
             <title>Version 1.3.0</title>
             <link>https://github.com/Bengerthelorf/macIconChanger</link>