[build] add placeholder ios.version.code

Author: Him188

gradle.properties

@@ -20,6 +20,8 @@ org.gradle.configuration-cache=true
 # major(1)-minor(pad to 2)-patch(1)-meta(1)
 # \u8FD9\u4E2A\u4E0D\u4F1A\u66F4\u65B0, \u4F46\u7531\u4E8E\u4E00\u6B21\u5931\u8BEF, \u5B83\u88AB\u66F4\u65B0\u5230\u4E86 50406
 android.version.code=50406
+# CI automatically replaces this
+ios.version.code=50406
 # TODO AGP Migration: Test android sdk 36
 android.compile.sdk=36
 android.min.sdk=27