Fix testParseAppcast failing on macOS 26 (#2772)

In the appcast there is an item with minimum OS requirement set to 17.0, which was never meant to be satisfied.

Author: zorgiepoo

Tests/Resources/testappcast.xml

@@ -39,7 +39,7 @@
         <sparkle:version>4.0</sparkle:version>
         <pubDate>Sat, 26 Jul 2014 15:20:13 +0000</pubDate>
         <enclosure url="http://localhost:1337/Sparkle_Test_App.zip" length="1346234" />
-        <sparkle:minimumSystemVersion>17.0.0</sparkle:minimumSystemVersion>
+        <sparkle:minimumSystemVersion>9999.0.0</sparkle:minimumSystemVersion>
     </item>
     <!-- A joke release testing maximumSystemVersion -->
     <item>