IronSource/update_changelog (#398)

Update the changelog to indicate that IronSource adapter version
8.5.0.0.0 requires minimum Xcode v15.3.

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## Description by Korbit AI

### What change is being made?
Update the IronSource changelog to include the new minimum Xcode
requirement of 15.3 for version 8.5.0.0.0.

### Why are these changes being made?
The change ensures users are informed of the updated development
environment requirements necessary to use the latest IronSource SDK
features and improvements, thereby helping to avoid potential
integration issues.

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IronSource/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 8.5.0.0.0
 * Certified with IronSource SDK 8.5.0.0.
+* Updated minimum Xcode requirement to 15.3.
 * Removed redundant log output when initialization was already completed.
 
 ## 8.4.0.0.0