Update rapier3d requirement from 0.20 to 0.21

Updates the requirements on [rapier3d](https://github.com/dimforge/rapier) to permit the latest version.
- [Changelog](https://github.com/dimforge/rapier/blob/master/CHANGELOG.md)
- [Commits](dimforge/rapier@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: rapier3d
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

bevy_rapier3d/Cargo.toml

@@ -47,7 +47,7 @@ async-collider = ["bevy/bevy_asset", "bevy/bevy_scene"]
 [dependencies]
 bevy = { version = "0.14.0-rc.3", default-features = false }
 nalgebra = { version = "0.32.6", features = ["convert-glam027"] }
-rapier3d = "0.20"
+rapier3d = "0.21"
 bitflags = "2.4"
 log = "0.4"
 serde = { version = "1", features = ["derive"], optional = true }