Bump System.Reactive from 4.0.0 to 4.1.5

Bumps [System.Reactive](https://github.com/dotnet/reactive) from 4.0.0 to 4.1.5.
- [Release notes](https://github.com/dotnet/reactive/releases)
- [Commits](dotnet/reactive@rxnet-v4.0.0...rxnet-v4.1.5)

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

Zeroconf/Zeroconf.csproj

@@ -20,7 +20,7 @@
     <PackageReference Include="Nerdbank.GitVersioning" Version="2.1.23" PrivateAssets="all" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0-beta-62925-02" PrivateAssets="all" />
     <PackageReference Include="RefactoringEssentials" Version="5.6.0" PrivateAssets="all" />
-    <PackageReference Include="System.Reactive" Version="4.0.0" />
+    <PackageReference Include="System.Reactive" Version="4.1.5" />
   </ItemGroup>
 
   <Target Name="AddCommitHashToAssemblyAttributes" BeforeTargets="GetAssemblyAttributes">