fix: void func had return, flutter displayed Error msg, fixed by removing return

[hu8813]

Feature summary

QA checklist

• Read state (state & power state)
• Read primary battery SOC
• Read primary battery cycles
• Read secondary battery SOC
• Read secondary battery cycles
• Read seat closed
• Read handlebar
• Read AUX SOC
• Read CBB SOC
• Read CBB charging state
• Update ping
• SOCs are cached (after app restart)
• Commands can be sent (locking & hibernation)

[TheFreal]

Well noticed! This is due to a recent change in https://github.com/chipweinberger/flutter_blue_plus, and should be fixed in version 1.2.4.