removed current_volume from _position_for_aspirate to avoid state errors
removed current_volume from _position_for_aspirate to avoid state errors

OpenTrons/opentrons-api,OpenTrons/opentrons_sdk,OpenTrons/opentrons-api,Opentrons/labware,OpenTrons/opentrons-api,OpenTrons/opentrons-api,OpenTrons/opentrons-api