Changes to Get company holdings

the response property holdings/items/end became nullable for the status 200

the response property holdings/items/percentage_share became nullable for the status 200

the response property holdings/items/start became nullable for the status 200

api tag v1 added

the response property holdings/items/end became required for the status 200

the response property holdings/items/percentage_share became required for the status 200

the response property holdings/items/start became required for the status 200

endpoint added