Remove variadic interface{}
Remove variadic interface{}

This fixes a panic:

panic: interface conversion: interface {} is []interface {}, not *pulseaudio.Config

goroutine 36 [running]:
panic(0x702ac0, 0xc4201b4740)
	/usr/lib/go/src/runtime/panic.go:500 +0x1a1
github.com/rumpelsepp/i3gostatus/lib/modules/pulseaudio.onWheelUp(0xc420151500, 0xc420148240, 0x6e02a0, 0xc420204a20)
	/home/stefan/Go/src/github.com/rumpelsepp/i3gostatus/lib/modules/pulseaudio/click.go:34 +0x17b
github.com/rumpelsepp/i3gostatus/lib/model.(*ClickHandlers).NewListener(0x8cb2a0, 0xc420151500, 0xc420148240, 0xc4202c0bc0, 0x1, 0x1)
	/home/stefan/Go/src/github.com/rumpelsepp/i3gostatus/lib/model/click.go:28 +0x39e
created by github.com/rumpelsepp/i3gostatus/lib/modules/pulseaudio.(*Config).Run
	/home/stefan/Go/src/github.com/rumpelsepp/i3gostatus/lib/modules/pulseaudio/pulseaudio.go:102 +0x347
exit status 2

rumpelsepp/i3gostatus,rumpelsepp/i3gostatus