[CI] Fix iOS 15 setup (#3979)

Author: testableapple

.github/workflows/cron-checks.yml

@@ -30,7 +30,7 @@ jobs:
           - ios: "17.5"
             device: "iPhone 15 Pro"
             setup_runtime: true
-          - ios: "15.5"
+          - ios: "15.4"
             device: "iPhone 13 Pro"
             setup_runtime: true
       fail-fast: false
@@ -98,7 +98,7 @@ jobs:
           - ios: "16.4"
             device: "iPhone 14 Pro"
             setup_runtime: true
-          - ios: "15.5"
+          - ios: "15.4"
             device: "iPhone 13 Pro"
             setup_runtime: true
       fail-fast: false