Disable CERTS conformance test due to a buggy generator

See #5177

Author: lehins

libs/cardano-ledger-conformance/test/Test/Cardano/Ledger/Conformance/ExecSpecRule/MiniTrace.hs

@@ -165,7 +165,7 @@ spec = do
     prop
       "CERT"
       (withMaxSuccess 50 (minitraceProp @"CERT" @ConwayEra 50 nameTxCert))
-    prop
+    xprop
       "CERTS"
       ( withMaxSuccess
           50

libs/cardano-ledger-conformance/test/Test/Cardano/Ledger/Conformance/Spec/Conway.hs

@@ -31,7 +31,7 @@ spec = do
       prop "GOVCERT" $ conformsToImpl @"GOVCERT" @ConwayEra
       prop "POOL" $ conformsToImpl @"POOL" @ConwayEra
       prop "CERT" $ conformsToImpl @"CERT" @ConwayEra
-      prop "CERTS" $ conformsToImpl @"CERTS" @ConwayEra
+      xprop "CERTS" $ conformsToImpl @"CERTS" @ConwayEra
       prop "GOV" $ conformsToImpl @"GOV" @ConwayEra
       -- UTXO is disabled due to: https://github.com/IntersectMBO/cardano-ledger/issues/4876
       xprop "UTXO" $ conformsToImpl @"UTXO" @ConwayEra