Unable to build iOS target

Hi the android is working fine but when I build the iOS target it displays this error
```
Execution failed for task ':buildSrc:compileKotlin'.
> Error while evaluating property 'compilerOptions.jvmTarget' of task ':buildSrc:compileKotlin'.
   > Failed to calculate the value of property 'jvmTarget'.
      > Unknown Kotlin JVM target: 21
```