get https://api.zan.top/node/v1/eth/mainnet//eth/v1/validator/sync_committee_contribution
Produce a sync committee contribution.
Requests that the beacon node produce a sync committee contribution.
A 503 error must be returned if the block identified by the response
beacon_block_root is optimistic (i.e. the sync committee contribution
refers to a block that has not been fully verified by an execution engine).