Update to Bevy 0.18.0

[Buncys]

Contributing for the first time. Tried to update to bevy 0.18.0. Here are the changes:

• Updated Bevy to version 0.18.0 and other dependencies
• Made the cleanup warning generic because the previous match was removed from Bevy
• Made testbed examples' ui_example_systems run on EguiPrimaryContextPass instead of Update to prevent panics

Fixes #685

[Deniskore]

In my opinion rapier should be updated to 0.32.0
But this will entail additional changes.

[Buncys]

Is this something that should be done in this PR, or should it be a separate follow-up PR?

[Deniskore]

I am not a maintainer, let's ask @sebcrozet

In any case, you can try updating it. If it's too difficult, I can take care of it later in additional PR.