Bump System.Reactive from 5.0.0 to 6.0.1 in the system group

Bumps the system group with 1 update: [System.Reactive](https://github.com/dotnet/reactive).


Updates `System.Reactive` from 5.0.0 to 6.0.1
- [Release notes](https://github.com/dotnet/reactive/releases)
- [Commits](dotnet/reactive@ixnet-v5.0.0...ixnet-v6.0.1)

---
updated-dependencies:
- dependency-name: System.Reactive
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: system
...

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

Author: dependabot[bot]

src/Tests/Tests.csproj

@@ -10,7 +10,7 @@
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2" PrivateAssets="all" />
     <PackageReference Include="DotNetConfig" Version="1.0.6" />
-    <PackageReference Include="System.Reactive" Version="5.0.0" />
+    <PackageReference Include="System.Reactive" Version="6.0.1" />
     <PackageReference Include="Azure.Messaging.WebPubSub" Version="1.4.0" />
   </ItemGroup>