fix: initialize gpio-switch state to off on startup

s.state was never set when the initial value is "off" (the default),
leaving it as an empty string. Querying state before the first on/off
command printed "Current state: " with no value.

Signed-off-by: Fabian Wienand <fabian.wienand@blindspot.software>

Author: RiSKeD

pkg/module/gpio/gpio.go

@@ -256,6 +256,8 @@ func (s *Switch) Init() error {
 		return s.on()
 	}
 
+	s.state = off
+
 	return s.off()
 }