v5.12.2

PowerSystems v5.12.2

Diff since v5.12.1

Merged pull requests:

• allow for slack bus when building system (#1740) (@m-bossart)
• fix: resolve branch type override property for TapTransformer (#1747) (@mcllerena)
• add switched shunt control flag (#1750) (@m-bossart)

Closed issues:

• Remove Union{Float64, TimeSeriesKey} type definitions for structure fields (#1472)
• PSY6: fully remove stateful unit system (#1712)