Bump Nerdbank.GitVersioning from 3.3.37 to 3.4.228 in /Rx.NET/Source

Bumps [Nerdbank.GitVersioning](https://github.com/dotnet/Nerdbank.GitVersioning) from 3.3.37 to 3.4.228.
- [Release notes](https://github.com/dotnet/Nerdbank.GitVersioning/releases)
- [Commits](dotnet/Nerdbank.GitVersioning@v3.3.37...v3.4.228)

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

Rx.NET/Source/Directory.build.props

@@ -28,7 +28,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
-    <PackageReference Include="Nerdbank.GitVersioning" Version="3.3.37" PrivateAssets="all" />
+    <PackageReference Include="Nerdbank.GitVersioning" Version="3.4.228" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(IsTestProject)' == 'true'">