Upgrade dependencies and target frameworks

ci/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/dotnet:2.1-sdk
+FROM mcr.microsoft.com/dotnet/core/sdk:3.0
 
 # Install dependencies:
 RUN apt-get update && apt-get install -y \
@@ -26,6 +26,6 @@ WORKDIR /opt/neo-cli-github
 # Build the project
 RUN dotnet restore
 RUN dotnet publish -c Release
-RUN mv bin/Release/netcoreapp2.1/publish /opt/neo-cli
+RUN mv bin/Release/netcoreapp3.0/publish /opt/neo-cli
 
 WORKDIR /opt

neo-cli/neo-cli.csproj

@@ -1,13 +1,14 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <Copyright>2016-2019 The Neo Project</Copyright>
     <AssemblyTitle>Neo.CLI</AssemblyTitle>
     <Version>3.0.0-preview1</Version>
     <Authors>The Neo Project</Authors>
-    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <AssemblyName>neo-cli</AssemblyName>
     <OutputType>Exe</OutputType>
+    <PublishReadyToRun>false</PublishReadyToRun>
     <PackageId>Neo.CLI</PackageId>
     <RootNamespace>Neo</RootNamespace>
     <Company>The Neo Project</Company>