Bump reactiveui from 18.4.44 to 19.2.1

Bumps [reactiveui](https://github.com/reactiveui/reactiveui) from 18.4.44 to 19.2.1.
- [Release notes](https://github.com/reactiveui/reactiveui/releases)
- [Commits](reactiveui/ReactiveUI@18.4.44...19.2.1)

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

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

Author: dependabot[bot]

IDisposableAnalyzers.Test/IDisposableAnalyzers.Test.csproj

@@ -45,6 +45,6 @@
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.435" PrivateAssets="all" />
     <PackageReference Include="System.Reactive.Linq" Version="6.0.0" />
-    <PackageReference Include="reactiveui" Version="18.4.44" />
+    <PackageReference Include="reactiveui" Version="19.2.1" />
   </ItemGroup>
 </Project>

ValidCode/ValidCode.csproj

@@ -27,6 +27,6 @@
     <PackageReference Include="Ninject" Version="3.3.6" />
     <PackageReference Include="NUnit" Version="3.13.3" />
     <PackageReference Include="System.Reactive.Linq" Version="6.0.0" />
-    <PackageReference Include="reactiveui" Version="18.4.44" />
+    <PackageReference Include="reactiveui" Version="19.2.1" />
   </ItemGroup>
 </Project>