Update dependency Microsoft.Owin.SelfHost to 4.2.3

Author: dependencyupdates[bot]

src/ServicePulse.Host/ServicePulse.Host.csproj

@@ -14,7 +14,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNet.WebApi.Owin" Version="5.3.0" />
-    <PackageReference Include="Microsoft.Owin.SelfHost" Version="4.2.2" />
+    <PackageReference Include="Microsoft.Owin.SelfHost" Version="4.2.3" />
     <PackageReference Include="Particular.Packaging" Version="4.5.0" PrivateAssets="All" />
   </ItemGroup>