Update to .net core 3.1

Author: cnblogs-dudu

src/Cuiliang.AliyunOssSdk.csproj

@@ -1,20 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <PackageId>aliyun.sdk.oss</PackageId>
-    <Version>0.3.3</Version>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
     <Description>Aliyun OSS SDK for .NET Core</Description>
-    <PackageTags>Aliyun</PackageTags>
+    <PackageTags>aliyun</PackageTags>
     <Authors>Cuiliang</Authors>
     <PackageProjectUrl>https://github.com/cnblogs/Cuiliang.AliyunOssSdk</PackageProjectUrl>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
   </PropertyGroup>
+
   <ItemGroup>
-    <Folder Include="Properties\" />
-  </ItemGroup>
-  <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="2.2.0" />
-    <PackageReference Include="Microsoft.Extensions.Http" Version="2.2.0" />
-    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="2.2.0" />
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
   </ItemGroup>
+
 </Project>

tests/Sample/Sample.csproj

@@ -1,18 +1,12 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <PropertyGroup>
     <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Cuiliang.AliyunOssSdk.csproj" />
   </ItemGroup>
-  <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.Configuration" Version="2.2.0" />
-    <PackageReference Include="Microsoft.Extensions.Configuration.FileExtensions" Version="2.2.0" />
-    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="2.2.0" />
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.2.0" />
-  </ItemGroup>
 </Project>