IOS 15.3.1 build 19D52

iOS 15.3.1 build 19D52 is the official RTM build of iOS 15.3.1, which was released to the public on 10 February 2022.

Fixes

 * Fixed an issues that sometimes caused Braille displays to stop responding.
 * A bug in WebKit that caused arbitrary code execution if malicious web content is executed was patched.