Target netcoreapp2.1 for codegen

Author: ncave

fcs/fcs-fable/codegen/codegen.fsproj

@@ -7,7 +7,8 @@
   <!-- <Import Project="fssrgen.targets" /> -->
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <RollForward>Major</RollForward>
   </PropertyGroup>
   <ItemGroup>
     <!-- <FsSrGen Include="$(FSharpSourcesRoot)\fsharp\FSComp.txt">

fcs/fcs-fable/fcs-fable.fsproj

@@ -231,7 +231,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="FSharp.Core" Version="4.6.2" />
+    <PackageReference Include="FSharp.Core" Version="4.7.0" />
   </ItemGroup>
 
 </Project>