build(deps): bump ReactiveUI from 16.3.5 to 16.3.9 in /src (#807)

Bumps [ReactiveUI](https://github.com/reactiveui/reactiveui) from 16.3.5 to 16.3.9.
- [Release notes](https://github.com/reactiveui/reactiveui/releases)
- [Commits](reactiveui/ReactiveUI@16.3.5...16.3.9)

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

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

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

src/ReactiveUI.DI.Tests/ReactiveUI.DI.Tests.csproj

@@ -47,7 +47,7 @@
   </Choose>
 
   <ItemGroup>
-    <PackageReference Include="ReactiveUI" Version="16.3.5" />
+    <PackageReference Include="ReactiveUI" Version="16.3.9" />
   </ItemGroup>
 
 </Project>