params, core/forkid: enable cancun on sepolia and holesky (#28834)

This change enables Cancun 

- Sepolia at 1706655072 (Jan 31st, 2024)
- Holesky at 1707305664 (Feb 7th, 2024)

Specification: https://github.com/ethereum/execution-specs/pull/860

params/config.go

@@ -81,6 +81,7 @@ var (
 		TerminalTotalDifficultyPassed: true,
 		MergeNetsplitBlock:            nil,
 		ShanghaiTime:                  newUint64(1696000704),
+		CancunTime:                    newUint64(1707305664),
 		Ethash:                        new(EthashConfig),
 	}
 	// SepoliaChainConfig contains the chain parameters to run a node on the Sepolia test network.
@@ -105,6 +106,7 @@ var (
 		TerminalTotalDifficultyPassed: true,
 		MergeNetsplitBlock:            big.NewInt(1735371),
 		ShanghaiTime:                  newUint64(1677557088),
+		CancunTime:                    newUint64(1706655072),
 		Ethash:                        new(EthashConfig),
 	}
 	// GoerliChainConfig contains the chain parameters to run a node on the Görli test network.