Update stale.yml (#1143)
Update stale.yml (#1143)

- Update Stale bot
  - Remove pulls: keyword - https://github.com/PowerShell/DscResources/issues/401#issuecomment-395959646.
  - Change stale label to 'stale' - https://github.com/PowerShell/DscResources/issues/401#issuecomment-395959646.
PowerShell/xSQLServer,johlju/xSQLServer,bozho/xSQLServer,nabrond/xSQLServer