Run Keystone and WordPressData unit tests in CI on iOS 18.4

The only iOS version available out of the box with the 16.3 stack.

Author: mokagio

.buildkite/pipeline.yml

@@ -121,7 +121,7 @@ steps:
           .buildkite/commands/shared-set-up.sh
           xcodebuild \
             -scheme Keystone \
-            -destination 'platform=iOS Simulator,OS=18.2,name=iPhone 16' \
+            -destination 'platform=iOS Simulator,OS=18.4,name=iPhone 16' \
             test \
             | xcbeautify
         plugins: [$CI_TOOLKIT_PLUGIN]
@@ -141,7 +141,7 @@ steps:
           .buildkite/commands/shared-set-up.sh
           xcodebuild \
             -scheme WordPressData \
-            -destination 'platform=iOS Simulator,OS=18.2,name=iPhone 16' \
+            -destination 'platform=iOS Simulator,OS=18.4,name=iPhone 16' \
             test \
             | xcbeautify
         plugins: [$CI_TOOLKIT_PLUGIN]