Misleading Error Message on Misconfigured Stage

[JesusMcCloud]

As per https://github.com/veehaitch/devicecheck-appattest/blob/main/src/main/kotlin/ch/veehait/devicecheck/appattest/attestation/AttestationValidator.kt#L268, the error message indicates, that a misconfiguration of development or production stage is not an issue, when in fact mixing up the stages can trigger this exception.