Remove NETStandard.Library dependency as implicit.

https://aka.ms/sdkimplicitrefs

Author: pavel-alay

itext.tests/itext.html2pdf.tests/itext.html2pdf.tests.netstandard.csproj

@@ -25,11 +25,6 @@
     <StartupObject />
     <AssemblyName>itext.html2pdf.tests</AssemblyName>
   </PropertyGroup>
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">
-    <PackageReference Include="Microsoft.NETCore.App">
-      <Version>1.0.0</Version>
-    </PackageReference>
-  </ItemGroup>
   <ItemGroup>
     <PackageReference Include="TeamCity.VSTest.TestAdapter" Version="1.0.0" />
     <PackageReference Include="NUnit" Version="3.7.1" />

itext/itext.html2pdf/itext.html2pdf.netstandard.csproj

@@ -20,9 +20,6 @@
     <AssemblyName>itext.html2pdf</AssemblyName>
     <RootNamespace />
   </PropertyGroup>
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.6' ">
-    <PackageReference Include="NETStandard.Library" Version="1.6.1" />
-  </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'net40' ">
     <Reference Include="System" />
     <Reference Include="System.Core" />

pdfHTML.nuspec

@@ -24,7 +24,6 @@
       <group targetFramework="netstandard1.6">
         <dependency id="itext7" version="7.1.6-SNAPSHOT" />
         <dependency id="Common.Logging" version="3.4.1" />
-        <dependency id="NETStandard.Library" version="1.6.1" />
       </group>
     </dependencies>
   </metadata>