Fix Conway CDDL spec to reflect no support of PV12

Author: lehins

eras/conway/impl/cddl-files/conway.cddl

@@ -125,7 +125,7 @@ signature = bytes .size 64
 
 protocol_version = [major_protocol_version, uint]
 
-major_protocol_version = 0 .. 12
+major_protocol_version = 0 .. 11
 
 transaction_body = 
   {   0  : set<transaction_input>         

eras/conway/impl/testlib/Test/Cardano/Ledger/Conway/CDDL.hs

@@ -13,7 +13,9 @@ module Test.Cardano.Ledger.Conway.CDDL (
   module Test.Cardano.Ledger.Conway.CDDL,
 ) where
 
+import Cardano.Ledger.BaseTypes (getVersion)
 import Cardano.Ledger.Conway (ConwayEra)
+import Cardano.Ledger.Core
 import Codec.CBOR.Cuddle.Comments ((//-))
 import Codec.CBOR.Cuddle.Huddle
 import Data.Function (($))
@@ -155,7 +157,12 @@ header_body =
       ]
 
 protocol_version :: Rule
-protocol_version = "protocol_version" =:= arr [a $ major_protocol_version @ConwayEra, a VUInt]
+protocol_version = "protocol_version" =:= arr [a $ conway_major_protocol_version, a VUInt]
+
+conway_major_protocol_version :: Rule
+conway_major_protocol_version =
+  "major_protocol_version"
+    =:= (getVersion @Integer (eraProtVerLow @ByronEra) ... getVersion @Integer (eraProtVerHigh @ConwayEra))
 
 transaction_body :: Rule
 transaction_body =