Scottish Greens must aim to return a record number of MSPs at next year's Holyrood elections, the party's co-leaders will say today.Patrick Harvie and Lorna Slater will tell members that environmental issues must be at the forefront of voters' mind and will defend their party's record at the Scottish Parliament over the last four years.The Scottish Greens' virtual conference began yesterday with a speech from Harvie calling for all Scottish Government contracts to be subject to trade union