v0.20.1

PowerSystems v0.20.1

Diff since v0.20.0

Merged pull requests:

• Add new AVR models (#515) (@rodrigomha)
• updating test for new rts hydro energy forecasts (#516) (@claytonpbarrows)
• update the addition of services (#517) (@jd-lara)
• forgot one (#518) (@claytonpbarrows)
• Add set dynamic injector for MultiThermalStart (#519) (@rodrigomha)
• pwl-origin-cost (#520) (@claytonpbarrows)
• fix function signature (#522) (@jd-lara)