Update to Bevy 0.12

[GitGhillie]

Closes #59
The only relevant migration seems to be:
FixedTime to Time (Bevy pull 8964)

To do:

• Test Doppler
• Update Bevy dependency to 0.12
• Remove smooth-bevy-cameras dev dependency so we don't have to wait for it (it got updated)

[GitGhillie]

Blocked on Bevy 0.12 release and #61, other than that it should be good to go

[GitGhillie]

Not blocking on 61 anymore since smooth-bevy-cameras got updated to 0.12

[pop]

@GitGhillie I think the README also needs to be updated if this version is compatible with Bevy 0.12.

[GitGhillie]

Thanks, I forgot about that! @Salzian did you want to do a final release before switching to 0.12? That will affect the version table.

[pop]

@GitGhillie @Salzian I can use this branch for now, but I would really appreciate this PR being merged so it officially supports Bevy 0.12. Is there anything I can do to help? Testing, etc?

[GitGhillie]

@pop we'll probably need to fix the issue mentioned above before it gets accepted. I put a small update in the thread if you want to look into it. Coming weekend I should have time to continue the investigation again

[GitGhillie]

Delaying the delta time by one frame fixed the unstable Doppler effect

[Salzian]

Accepting this for now, as I can't reproduce the unstable Doppler effect.