THRIFT-4990 Switch to .NET core 3.0
Client: netstsd
Patch: Jens Geyer

This closes #1909
diff --git a/tutorial/netstd/Client/Client.csproj b/tutorial/netstd/Client/Client.csproj
index a1470a9..2abf53c 100644
--- a/tutorial/netstd/Client/Client.csproj
+++ b/tutorial/netstd/Client/Client.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <AssemblyName>Client</AssemblyName>
     <PackageId>Client</PackageId>
     <OutputType>Exe</OutputType>
diff --git a/tutorial/netstd/Interfaces/Interfaces.csproj b/tutorial/netstd/Interfaces/Interfaces.csproj
index 4ebeb4f..2d8a440 100644
--- a/tutorial/netstd/Interfaces/Interfaces.csproj
+++ b/tutorial/netstd/Interfaces/Interfaces.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netstandard2.1</TargetFramework>
     <AssemblyName>Interfaces</AssemblyName>
     <PackageId>Interfaces</PackageId>
     <GenerateAssemblyConfigurationAttribute>false</GenerateAssemblyConfigurationAttribute>
diff --git a/tutorial/netstd/README.md b/tutorial/netstd/README.md
index b1dea4e..11fd541 100644
--- a/tutorial/netstd/README.md
+++ b/tutorial/netstd/README.md
@@ -1,11 +1,11 @@
 # Building of samples for different platforms 
 
 # Reused components 
-- NET Core Standard 2.0
-- NET Core App 2.0
+- NET Core Standard 3.0
+- NET Core App 3.0
 
 # How to build
-- Download and install the latest .NET Core SDK for your platform https://www.microsoft.com/net/core#windowsvs2015 (archive for SDK 1.0.0-preview2-003121 located by: https://github.com/dotnet/core/blob/master/release-notes/download-archive.md)
+- Download and install the latest .NET Core SDK for your platform https://dotnet.microsoft.com/download/dotnet-core
 - Ensure that you have thrift.exe which supports netstd lib and it added to PATH 
 - Go to current folder 
 - Run **build.sh** or **build.cmd** from the root of cloned repository
diff --git a/tutorial/netstd/Server/Program.cs b/tutorial/netstd/Server/Program.cs
index 25e7dae..e1dab01 100644
--- a/tutorial/netstd/Server/Program.cs
+++ b/tutorial/netstd/Server/Program.cs
@@ -346,7 +346,7 @@
 
             public class Startup
             {
-                public Startup(IHostingEnvironment env)
+                public Startup(IWebHostEnvironment env)
                 {
                     var builder = new ConfigurationBuilder()
                         .SetBasePath(env.ContentRootPath)
@@ -366,7 +366,7 @@
                 }
 
                 // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
-                public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
+                public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerFactory loggerFactory)
                 {
                     app.UseMiddleware<THttpServerTransport>();
                 }
diff --git a/tutorial/netstd/Server/Server.csproj b/tutorial/netstd/Server/Server.csproj
index fbc2c03..454f332 100644
--- a/tutorial/netstd/Server/Server.csproj
+++ b/tutorial/netstd/Server/Server.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <AssemblyName>Server</AssemblyName>
     <PackageId>Server</PackageId>
     <OutputType>Exe</OutputType>