Bug 1814: Add /bin/sh to the list of shells

https://winscp.net/tracker/1814

Source commit: 5b6279c1927944c20bc47823b85bb50761019422

source/forms/SiteAdvanced.dfm

@@ -773,6 +773,7 @@ object SiteAdvancedDialog: TSiteAdvancedDialog
               'Default'
               '/bin/bash'
               '/bin/ksh'
+              '/bin/sh'
               'sudo su -')
           end
           object ReturnVarEdit: TComboBox