Bump version, update egui/bevy dependency version

[dymk]

• Updates Bevy dependency to be the latest @ 0.10.1
• Updates Egui dependency to be the latest @ 0.22.0

And bump the crate version to 0.20.4, as the change as not backwards compatible for projects pinned at different bevy/egui versions.

Perhaps there's a better way to make bevy_egui agnostic to specific bevy/egui versions? They're pre-1.x.y, so semver doesn't make compatibility guarentees, but I'm hoping the crates don't have to be pinned at the patch version.

[mvlabat]

Hey! Thank you for the PR. I'll close this in favour of #184, as it has conflicts in Cargo.toml after updating to Bevy 0.11 now.
My apologies for not checking it sooner.