Keep AddressSpecification from being obfuscated

We are mapping country codes the this enum's entries. This will not
work if the enum is obfuscated.

COAND-777

card/src/main/java/com/adyen/checkout/card/ui/AddressSpecification.kt

@@ -9,14 +9,16 @@
 
 package com.adyen.checkout.card.ui
 
+import androidx.annotation.Keep
 import androidx.annotation.StyleRes
 import com.adyen.checkout.card.R
 
 /**
  * Specification for address form alternatives depending on the country.
  */
 @Suppress("LongParameterList")
-enum class AddressSpecification(
+@Keep
+internal enum class AddressSpecification(
     internal val street: AddressFieldSpec,
     internal val houseNumber: AddressFieldSpec,
     internal val apartmentSuite: AddressFieldSpec,