Remove framework gating

PortableExecutable/FontGroupHeader.cs

@@ -16,10 +16,6 @@
         /// A structure that contains a unique ordinal identifier for each font in the resource. The DE
         /// member is a placeholder for the variable-length array of DIRENTRY structures.
         /// </summary>
-#if NET48
-        public DirEntry[] DE { get; set; }
-#else
         public DirEntry?[]? DE { get; set; }
-#endif
     }
 }