Add Kotlin jvmTarget

Without this, the build fails for me with (likely because my installation defaults to Java 21):

Execution failed for task ':app:compileFullDebugKotlin'.
> Inconsistent JVM-target compatibility detected for tasks 'compileFullDebugJavaWithJavac' (17) and 'compileFullDebugKotlin' (21).

app/build.gradle

@@ -102,6 +102,10 @@ android {
         targetCompatibility JavaVersion.VERSION_17
     }
 
+    kotlinOptions {
+        jvmTarget = '17'
+    }
+
     aaptOptions {
         cruncherEnabled = false
     }