Replace consensus version calls

[hweawer]

What

get rid of self.report_contract.get_consensus_version()

Things to consider

I can't replace it in:

    def _check_contract_versions(self, blockstamp: ReferenceBlockStamp):
        """
        Check if Oracle can process report on reference blockstamp.
        """
        self._check_compatability(blockstamp.block_hash)
        self._check_compatability('latest')

    def _check_compatability(self, block_tag: BlockIdentifier):
        contract_version = self.report_contract.get_contract_version(block_tag)
        consensus_version = self.report_contract.get_consensus_version(block_tag)

        compatibility = (contract_version, consensus_version) in self.COMPATIBLE_ONCHAIN_VERSIONS

        if not compatibility:
            raise IncompatibleOracleVersion(
                f'Incompatible Oracle version. Block tag: {repr(block_tag)}. '
                f'Expected (Contract, Consensus) versions: {', '.join(repr(v) for v in self.COMPATIBLE_ONCHAIN_VERSIONS)}, '
                f'Got ({contract_version}, {consensus_version})'
            )