Update Podfile.template: update macOS target version from 13.3 to 13.4 (microsoft#25699)

### Description
This change should be included in PR microsoft#25616. I missed it.


### Motivation and Context
Currently our iOS packaging pipeline is failing because of this.

Author: snnn

onnxruntime/test/platform/apple/apple_package_test/Podfile.template

@@ -15,7 +15,7 @@ if ENV['SKIP_MACOS_TEST'] != 'true'
       # Comment the next line if you don't want to use dynamic frameworks
       use_frameworks!
 
-      platform :osx, '13.3'
+      platform :osx, '13.4'
 
       target 'macos_package_testUITests' do
         inherit! :search_paths