Fix nupkg version conflict.

Author: yfakariya

test/MsgPack.UnitTest/MsgPack.UnitTest.csproj

@@ -23,13 +23,13 @@
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp1.0'">
     <PackageReference Include="Microsoft.CSharp" Version="4.0.1" />
-    <PackageReference Include="System.Collections.NonGeneric" Version="4.0.1" />
-    <PackageReference Include="System.Collections.Specialized" Version="4.0.1" />
+    <PackageReference Include="System.Collections.NonGeneric" Version="4.3.0" />
+    <PackageReference Include="System.Collections.Specialized" Version="4.3.0" />
     <PackageReference Include="System.Data.Common" Version="4.1.0" />
     <PackageReference Include="System.Diagnostics.Contracts" Version="4.0.1" />
     <PackageReference Include="System.Numerics.Vectors" Version="4.1.1" />
-    <PackageReference Include="System.Runtime.Numerics" Version="4.0.1" />
-    <PackageReference Include="System.Runtime.Serialization.Primitives" Version="4.1.1" />
+    <PackageReference Include="System.Runtime.Numerics" Version="4.3.0" />
+    <PackageReference Include="System.Runtime.Serialization.Primitives" Version="4.3.0" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'net46'">
     <Reference Include="System" />