继续降级运行时版本，用于方便龙芯和项目集成

Author: lindexi

src/MediaConverters/MediaConverters.Lib/MediaConverters.Lib.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <AssemblyName>DotNetCampus.MediaConverters</AssemblyName>
     <RootNamespace>$(AssemblyName)</RootNamespace>

src/MediaConverters/MediaConverters.Tool.RuntimeNuGet/MediaConverters.Tool.RuntimeNuGet.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <!-- 
       配置为无依赖。即避免带上 TargetFramework=netstandard2.0 的限制
       配合 IncludeBuildOutput=false 即可让任意项目引用，无视目标框架

src/MediaConverters/MediaConverters.Tool/MediaConverters.Tool.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <RootNamespace>DotNetCampus.MediaConverters</RootNamespace>
     <!-- 故意去掉 s 方便生成名为 DotNetCampus.MediaConverter.exe 的文件 -->

src/MediaConverters/SkiaWmfRenderer/src/SkiaWmfRenderer/SkiaWmfRenderer.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net9.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <LangVersion>latest</LangVersion>

src/MediaConverters/SkiaWmfRenderer/src/wieslawsoltes-wmf/src/library/Library.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net9.0;</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0;</TargetFrameworks>
     <OutputType>Library</OutputType>
     <RootNamespace>Oxage.Wmf</RootNamespace>
     <AssemblyName>Oxage.Wmf</AssemblyName>