Fix .NET Core *.nuspec

Author: xplicit

NuGet.Core/ServiceStack.Text.Core/servicestack.text.core.nuspec

@@ -30,7 +30,7 @@
          <dependency id="NETStandard.Library" version="[1.6.0, )" />
       </group>
       <group targetFramework=".NETStandard1.3">
-        <dependency id="System.Runtime.Serialization.Primitives" version="[4.1.1
+        <dependency id="System.Runtime.Serialization.Primitives" version="[4.1.1, )" />
         <dependency id="System.Runtime.Serialization.Xml" version="[4.1.1, )" />
         <dependency id="System.Net.Requests" version="[4.0.11, )" />
         <dependency id="System.Dynamic.Runtime" version="[4.0.11, )" />