restrict mixing to mainnet and testnet

src/main/java/com/sparrowwallet/sparrow/wallet/UtxosController.java

@@ -140,7 +140,10 @@ public class UtxosController extends WalletFormController implements Initializab
     }
 
     private boolean canWalletMix() {
-        return getWalletForm().getWallet().getKeystores().size() == 1 && getWalletForm().getWallet().getKeystores().get(0).hasSeed() && !getWalletForm().getWallet().isWhirlpoolMixWallet();
+        return Whirlpool.WHIRLPOOL_NETWORKS.contains(Network.get())
+                && getWalletForm().getWallet().getKeystores().size() == 1
+                && getWalletForm().getWallet().getKeystores().get(0).hasSeed()
+                && !getWalletForm().getWallet().isWhirlpoolMixWallet();
     }
 
     private void updateButtons(BitcoinUnit unit) {

src/main/java/com/sparrowwallet/sparrow/whirlpool/Whirlpool.java

@@ -59,6 +59,7 @@ import java.util.stream.Collectors;
 public class Whirlpool {
     private static final Logger log = LoggerFactory.getLogger(Whirlpool.class);
 
+    public static final List<Network> WHIRLPOOL_NETWORKS = List.of(Network.MAINNET, Network.TESTNET);
     public static final int DEFAULT_MIXTO_MIN_MIXES = 5;
     public static final int DEFAULT_MIXTO_RANDOM_FACTOR = 4;