Add missing CastVerificationKeyRole StakePoolExtendedKey StakePoolKey instance

Author: carbolymer

cardano-api/src/Cardano/Api/Internal/Keys/Shelley.hs

@@ -1906,6 +1906,18 @@ instance SerialiseAsBech32 (SigningKey StakePoolExtendedKey) where
   bech32PrefixFor _ = "pool_xsk"
   bech32PrefixesPermitted _ = ["pool_xsk"]
 
+instance CastVerificationKeyRole StakePoolExtendedKey StakePoolKey where
+  castVerificationKey (StakePoolExtendedVerificationKey vk) =
+    StakePoolVerificationKey
+      . Shelley.VKey
+      . fromMaybe impossible
+      . Crypto.rawDeserialiseVerKeyDSIGN
+      . Crypto.HD.xpubPublicKey
+      $ vk
+   where
+    impossible =
+      error "castVerificationKey (StakePoolKey): byron and shelley key sizes do not match!"
+
 --
 -- DRep keys
 --