Make SetField accepts covaraince T

This allows using subclass of type T when setting a value for
SetField<T>.

Bug: 409261827
Test: ./gradlew :appfunctions:appfunctions-schema:kspReleaseKotlin
Change-Id: I25f1a7c7d1770931e572a9e6dfb9fd07281b340d
diff --git a/appfunctions/appfunctions-schemas/src/main/java/androidx/appfunctions/schema/types/SetField.kt b/appfunctions/appfunctions-schemas/src/main/java/androidx/appfunctions/schema/types/SetField.kt
index 5d93a59..07af6ee 100644
--- a/appfunctions/appfunctions-schemas/src/main/java/androidx/appfunctions/schema/types/SetField.kt
+++ b/appfunctions/appfunctions-schemas/src/main/java/androidx/appfunctions/schema/types/SetField.kt
@@ -52,7 +52,7 @@
  * @param value The new field value.
  */
 @AppFunctionSerializable
-public class SetField<T>(public val value: T) {
+public class SetField<out T>(public val value: T) {
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (other !is SetField<*>) return false