Input manager doesn't tear down connections before creating new ones

[alexzobi]

While using the visualizer, I noticed that the visualizer would detect keyboard input on every other entry into the playing scene. Looking at the code, it became clear that the input manager was attempting to reconnect on every scene change, but was never actually explicitly disconnecting. This is likely what is leading to the flakey behavior, which for me is 100% reproducible. Steps to reproduce:

1. start the app
2. select a midi file
3. click the "play" button to navigate to the playing_scene // input at this point behaves normally
4. hit the "back" button to return to the menu_scene.
5. hit the "play" button again to return to the playing_scene // inputs no longer work

[PolyMeilex]

Hi, what's your platform? Windows?

[PolyMeilex]

Could you test this fix: #357 ?

Works well on my win11 setup.