update to 4.6.1

Rx.NET/Source/benchmarks/Benchmarks.System.Reactive/Benchmarks.System.Reactive.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net46</TargetFramework>
+    <TargetFramework>net461</TargetFramework>
     <Optimize>true</Optimize>
     <IsPackable>false</IsPackable>
     <Configurations>Current Sources;Rx.net 3.1.1;Rx.net 4.0</Configurations>