update publish profile to core2.1

Author: watashiSHUN

src/WebJobs.Script.WebHost/Properties/PublishProfiles/FolderProfile.pubxml

@@ -15,6 +15,6 @@ by editing this MSBuild file. In order to learn more about this please visit htt
     <ProjectGuid>d5162088-c119-4a06-896d-e65983caedfd</ProjectGuid>
     <publishUrl>bin\Release\SiteExtensions\Functions</publishUrl>
     <DeleteExistingFiles>False</DeleteExistingFiles>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
   </PropertyGroup>
 </Project>