Update fyrox-ui requirement in /cvars-console-fyrox

Updates the requirements on [fyrox-ui](https://github.com/FyroxEngine/Fyrox) to permit the latest version.
- [Release notes](https://github.com/FyroxEngine/Fyrox/releases)
- [Changelog](https://github.com/FyroxEngine/Fyrox/blob/master/CHANGELOG.md)
- [Commits](https://github.com/FyroxEngine/Fyrox/commits/v0.21)

---
updated-dependencies:
- dependency-name: fyrox-ui
  dependency-type: direct:production
...

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

Author: dependabot[bot]

cvars-console-fyrox/Cargo.toml

@@ -20,4 +20,4 @@ categories = [
 [dependencies]
 cvars = { version = "0.3.0", path = "../cvars" }
 cvars-console = { version = "0.1.0", path = "../cvars-console" }
-fyrox-ui = "0.20.0"
+fyrox-ui = "0.21.0"