Bump ReactiveUI.Uwp from 18.2.5 to 18.3.1 in /src (#84)

Bumps [ReactiveUI.Uwp](https://github.com/reactiveui/reactiveui) from 18.2.5 to 18.3.1.
- [Release notes](https://github.com/reactiveui/reactiveui/releases)
- [Commits](https://github.com/reactiveui/reactiveui/compare/18.2.5...18.3.1)

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

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

src/Camelotia.Presentation.Uwp/Camelotia.Presentation.Uwp.csproj

@@ -216,7 +216,7 @@
       <Version>18.2.5</Version>
     </PackageReference>
     <PackageReference Include="ReactiveUI.Uwp">
-      <Version>18.2.5</Version>
+      <Version>18.3.1</Version>
     </PackageReference>
     <PackageReference Include="ReactiveMarbles.ObservableEvents.SourceGenerator" Version="1.1.4" PrivateAssets="all" />
   </ItemGroup>