Update min iOS in update-dependencies (#1777)

Author: a-maurice

.github/workflows/update-dependencies.yml

@@ -95,7 +95,7 @@ jobs:
               # Generate a Podfile for Firebase/Analytics. Use the Specs.git
               # source to avoid any propagation delays due to CocoaPods mirror.
               echo "source 'https://github.com/CocoaPods/Specs.git'" > Podfile
-              echo "platform :ios, '14.0'" >> Podfile
+              echo "platform :ios, '15.0'" >> Podfile
               echo "pod 'Firebase/Analytics', '${analytics_version}'" >> Podfile
               pod repo update
               pod install || true # ignore error since there is no Xcode project