chore!: retarget to netstandard2.0

Author: DocSvartz

src/Mapster.Core/Mapster.Core.csproj

@@ -1,9 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <Description>Lightweight library for Mapster and Mapster CodeGen</Description>
-    <TargetFrameworks>net9.0;net8.0;</TargetFrameworks>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>Mapster.Core</AssemblyName>
-    <PackageTags>mapster</PackageTags>
+    <PackageTags>Mapster</PackageTags>
     <Version>9.0.0-pre01</Version>
     <Nullable>enable</Nullable>
 	<IsPackable>true</IsPackable>

src/Sample.CodeGen/Sample.CodeGen.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net9.0;net8.0;</TargetFrameworks>
+    <TargetFrameworks>net10.0;net9.0;net8.0;</TargetFrameworks>
     <Nullable>enable</Nullable>
   </PropertyGroup>