Bump ReactiveUI.Fody from 17.1.50 to 18.3.1 (#86)

Bumps [ReactiveUI.Fody](https://github.com/reactiveui/reactiveui) from 17.1.50 to 18.3.1.
- [Release notes](https://github.com/reactiveui/reactiveui/releases)
- [Commits](https://github.com/reactiveui/reactiveui/compare/17.1.50...18.3.1)

---
updated-dependencies:
- dependency-name: ReactiveUI.Fody
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

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

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

@@ -13,7 +13,7 @@
     <PackageReference Include="Avalonia.LinuxFramebuffer" Version="0.10.12" />
     <PackageReference Include="Avalonia.Desktop" Version="0.10.12" />
     <PackageReference Include="ReactiveUI.Validation" Version="2.2.1" />
-    <PackageReference Include="ReactiveUI.Fody" Version="17.1.50" />
+    <PackageReference Include="ReactiveUI.Fody" Version="18.3.1" />
   </ItemGroup>
   
   <ItemGroup>