Account for extra approvals in the last header of the epoch

[MaksymZavershynskyi]

As explained here https://github.com/nearprotocol/nearcore/issues/3307

The approvals on the epoch boundary contains several extra approvals from the blockproducers of the next epoch, which are not present in the current.

This was not in the light client spec https://nomicon.io/ChainSpec/LightClient.html and Solidity implementation did not account for it.

[MaksymZavershynskyi]

Change looks good. need to increase rainbow-bridge-sol version number in package.json so we can publish new package

Done