fix(contract_manager): use public rpc for blast testnet (#1441)

Author: m30m

contract_manager/store/chains/EvmChains.yaml

@@ -450,7 +450,7 @@
   type: EvmChain
 - id: blast_s2_testnet
   mainnet: false
-  rpcUrl: https://rpc.s2.testblast.io/$ENV_BLAST_S2_TESTNET_API_KEY
+  rpcUrl: https://blast-sepolia.blockpi.network/v1/rpc/public
   networkId: 168587773
   type: EvmChain
 - id: hedera_testnet