Update egui to 0.30.0

[CUB3D]

No description provided.

[blitzarx1]

Hi! Build fails with the changes

[CUB3D]

Hi, this is because the examples also pin the version of egui and petgraph. Notably the following can't build on a newer petgraph version:

• demo because fdg depends on petgraph=0.6.4
• bevy_basic because bevy_reflect and bevy_ecs depend on petgraph=0.6.5

Personally I only need egui >= 0.30 so I'm ditching the update to petgraph due to time constraints, but I'll note that your library works fine on 0.7.1 - it's just these example dependencies that are borked.

Couple of extra points:

• The examples in examples/ aren't actually registered as examples in Cargo.toml which is why this was missed
• Having cargo.lock committed here might be a problem, as its ignored by library consumers. Hence this worked in my project while breaking the examples by pinning the versions. If it wasn't here then some of these would not have broken I think.