Target .NET Core 3.0 for NVDEC project

Ryujinx.Graphics.Nvdec/Ryujinx.Graphics.Nvdec.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">