build(deps): Bump Microsoft.Reactive.Testing from 5.0.0 to 6.0.0

Bumps [Microsoft.Reactive.Testing](https://github.com/dotnet/reactive) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/dotnet/reactive/releases)
- [Commits](https://github.com/dotnet/reactive/commits)

---
updated-dependencies:
- dependency-name: Microsoft.Reactive.Testing
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

src/ReactiveMarbles.CacheDatabase.Settings.Tests/ReactiveMarbles.CacheDatabase.Settings.Tests.csproj

@@ -20,7 +20,7 @@
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
     <PackageReference Include="FluentAssertions" Version="6.10.0" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="5.0.0" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.0" />
     <PackageReference Include="ReactiveUI.Testing" Version="18.4.26" />
   </ItemGroup>
 

src/ReactiveMarbles.CacheDatabase.Tests/ReactiveMarbles.CacheDatabase.Tests.csproj

@@ -22,7 +22,7 @@
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
     <PackageReference Include="FluentAssertions" Version="6.10.0" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="5.0.0" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.0" />
     <PackageReference Include="ReactiveUI.Testing" Version="18.4.26" />
   </ItemGroup>