get https://{server_url}/{api_key}/eth/v1/beacon/states//validator_balances
Returns filterable list of validators balances.
Balances will be returned for all indices or public key that match known validators. If an index or public key does not
match any known validator, no balance will be returned but this will not cause an error. There are no guarantees for the
returned data in terms of ordering; the index and is returned for each balance, and can be used to confirm for which inputs a
response has been returned.