Use license expression

Author: mnadareski

BurnOutSharp/BurnOutSharp.csproj

@@ -9,7 +9,7 @@
     <Authors>Matt Nadareski;Gernot Knippen</Authors>
     <Product>BurnOutSharp</Product>
     <Copyright>Copyright (c)2005-2010 Gernot Knippen, Copyright (c)2018-2022 Matt Nadareski</Copyright>
-    <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
+    <PackageLicenseExpression>GPL-3.0-only</PackageLicenseExpression>
     <RepositoryUrl>https://github.com/mnadareski/BurnOutSharp</RepositoryUrl>
     <Version>2.5</Version>
     <AssemblyVersion>2.5</AssemblyVersion>
@@ -45,10 +45,6 @@
     </DefaultItemExcludes>
   </PropertyGroup>
 
-  <ItemGroup>
-    <None Include="LICENSE.txt" Pack="true" PackagePath="$(PackageLicenseFile)" />
-  </ItemGroup>
-
   <ItemGroup>
     <None Include="*.dll" Pack="true" Condition="'$(TargetFramework)' != 'net6.0'">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>