update nuget description

Author: dameng324

src/CTPFuture.Net/CTPFuture.Net.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
-        <TargetFrameworks>net6.0;net8.0;netstandard2.0;net45;net46;</TargetFrameworks>
+        <TargetFrameworks>net6.0;net8.0;net9.0;netstandard2.0;net45;net46;</TargetFrameworks>
         <OutputType>Library</OutputType>
         <Nullable>enable</Nullable>
         <RepositoryType>git</RepositoryType>
@@ -13,7 +13,7 @@
         <RepositoryUrl>https://github.com/dameng324/CtpFuture.Net.git</RepositoryUrl>
         <PackageProjectUrl>https://github.com/dameng324/CtpFuture.Net</PackageProjectUrl>
         <Title>CTPFuture.Net</Title>
-        <Description>Provides simple access to fast and efficient "Protocol Buffers" serialization from .NET applications</Description>
+        <Description>CTP期货API的.NET库,支持现代化.NET8,NET9和旧版.NET Framework,以及.NetStandard</Description>
     </PropertyGroup>
 
     <ItemGroup>
@@ -33,7 +33,4 @@
             <PackagePath>include\%(FileName)%(Extension)</PackagePath>
         </Content>
     </ItemGroup>
-    <ItemGroup>
-        <PackageReference Condition="$(TargetFramework)=='netstandard2.0'" Include="System.Text.Encoding.CodePages" Version="9.0.0"/>
-    </ItemGroup>
 </Project>