Fixed licence reference

Author: droyad

src/Assent/Assent.csproj

@@ -13,6 +13,6 @@
     <Authors>droyad</Authors>
     <PackageProjectUrl>https://github.com/droyad/Assent</PackageProjectUrl>
     <RepositoryUrl>https://github.com/droyad/Assent</RepositoryUrl>
-    <PackageLicenseUrl>https://github.com/droyad/Assent/blob/master/LICENCE.md</PackageLicenseUrl>
+    <PackageLicense>MIT</PackageLicense>
   </PropertyGroup>
 </Project>