Bump xunit.runner.visualstudio from 2.4.1 to 2.4.3 in /Rx.NET/Source

Bumps [xunit.runner.visualstudio](https://github.com/xunit/visualstudio.xunit) from 2.4.1 to 2.4.3.
- [Release notes](https://github.com/xunit/visualstudio.xunit/releases)
- [Commits](https://github.com/xunit/visualstudio.xunit/commits/v2.4.3)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Rx.NET/Source/tests/Tests.System.Reactive.ApiApprovals/Tests.System.Reactive.ApiApprovals.csproj

@@ -28,7 +28,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />
     <PackageReference Include="Verify.Xunit" Version="1.34.2" />
     <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
     <PackageReference Include="DiffPlex" Version="1.6.3" />
     <PackageReference Include="PublicApiGenerator" Version="10.1.0" />
   </ItemGroup>

Rx.NET/Source/tests/Tests.System.Reactive/Tests.System.Reactive.csproj

@@ -19,7 +19,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />    
     <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
     <ProjectReference Include="..\..\src\System.Reactive\System.Reactive.csproj" />
     <ProjectReference Include="..\..\src\System.Reactive.Observable.Aliases\System.Reactive.Observable.Aliases.csproj" />
     <ProjectReference Include="..\..\src\Microsoft.Reactive.Testing\Microsoft.Reactive.Testing.csproj" />