Update System.Reactive to 6.1.0

Author: renovate[bot]

Directory.Packages.props

@@ -48,9 +48,9 @@
         <PackageVersion Include="System.Interactive" Version="6.0.3" />
         <PackageVersion Include="System.Interactive.Async" Version="6.0.3" />
         <PackageVersion Include="System.Text.Json" Version="8.0.6" />
-        <PackageVersion Include="System.Reactive" Version="6.0.2" />
-        <PackageVersion Include="System.Reactive.Observable.Aliases" Version="6.0.2" />
-        <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.0.2" />
+        <PackageVersion Include="System.Reactive" Version="6.1.0" />
+        <PackageVersion Include="System.Reactive.Observable.Aliases" Version="6.1.0" />
+        <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.1.0" />
         <PackageVersion Include="Bogus" Version="35.6.4" />
         <PackageVersion Include="Shouldly" Version="4.3.0" />
         <PackageVersion Include="Rocket.Surgery.Extensions.Testing.FakeItEasy" Version="10.0.0-beta.2" />