Bump System.Reactive from 5.0.0 to 6.0.0 (#1306)

Bumps [System.Reactive](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: System.Reactive
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

tests/KubernetesClient.Classic.Tests/KubernetesClient.Classic.Tests.csproj

@@ -11,7 +11,7 @@
       <PackageReference Include="FluentAssertions" Version="6.11.0" />
       <PackageReference Include="Microsoft.Extensions.Logging" Version="7.0.0" />
       <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="19.2.29" />
-      <PackageReference Include="System.Reactive" Version="5.0.0" />
+      <PackageReference Include="System.Reactive" Version="6.0.0" />
       <PackageReference Include="Nito.AsyncEx" Version="5.1.2" />
       <PackageReference Include="Portable.BouncyCastle" Version="1.9.0" />
   </ItemGroup>

tests/KubernetesClient.Tests/KubernetesClient.Tests.csproj

@@ -10,7 +10,7 @@
       <PackageReference Include="FluentAssertions" Version="6.11.0" />
       <PackageReference Include="Microsoft.Extensions.Logging" Version="7.0.0" />
       <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="19.2.29" />
-      <PackageReference Include="System.Reactive" Version="5.0.0" />
+      <PackageReference Include="System.Reactive" Version="6.0.0" />
       <PackageReference Include="Nito.AsyncEx" Version="5.1.2" />
       <PackageReference Include="Portable.BouncyCastle" Version="1.9.0" />
   </ItemGroup>