message: feat(fork): activate testnet since epoch 3113
diff: /// The Chain Specification name.
  pub const CHAIN_SPEC_NAME: &str = "ckb_testnet";
  -// TODO ckb2021 Update the epoch number for testnet.
  -/// First epoch number for CKB v2021
  -pub const CKB2021_START_EPOCH: u64 = u64::MAX;
  +/// First epoch number for CKB v2021, at about 2021/10/24 3:15 UTC.
  +pub const CKB2021_START_EPOCH: u64 = 3113;
  