Bump ReactiveUI.Validation from 2.1.1 to 2.2.1 (#27)

Bumps [ReactiveUI.Validation](https://github.com/reactiveui/reactiveui.validation) from 2.1.1 to 2.2.1.
- [Release notes](https://github.com/reactiveui/reactiveui.validation/releases)
- [Commits](reactiveui/ReactiveUI.Validation@2.1.1...2.2.1)

---
updated-dependencies:
- dependency-name: ReactiveUI.Validation
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Citrus.Avalonia.Sandbox/Citrus.Avalonia.Sandbox.csproj

@@ -12,7 +12,7 @@
     <PackageReference Include="Avalonia.ReactiveUI" Version="0.10.7" />
     <PackageReference Include="Avalonia.LinuxFramebuffer" Version="0.10.7" />
     <PackageReference Include="Avalonia.Desktop" Version="0.10.7" />
-    <PackageReference Include="ReactiveUI.Validation" Version="2.1.1" />
+    <PackageReference Include="ReactiveUI.Validation" Version="2.2.1" />
     <PackageReference Include="ReactiveUI.Fody" Version="16.2.6" />
   </ItemGroup>