Support the same targetframeworks as the main dependency

Author: RyadaProductions

src/FluentAssertions.Ioc.Ninject/FluentAssertions.Ioc.Ninject.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Library</OutputType>
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <TargetFrameworks>net47;netcoreapp2.1;netcoreapp3.0;netstandard2.0;netstandard2.1</TargetFrameworks>
     <RestorePackages>true</RestorePackages>
     <Version>1.4.0</Version>
     <Authors>Kevin Kuszyk</Authors>