Use System.Text.Json instead of Newtonsoft.Json

DiscordChatExporter.Core.Models/FileSize.cs

@@ -4,7 +4,7 @@ namespace DiscordChatExporter.Core.Models
 {
     // Loosely based on https://github.com/omar/ByteSize (MIT license)
 
-    public readonly struct FileSize
+    public readonly partial struct FileSize
     {
         public long TotalBytes { get; }
 
@@ -58,4 +58,9 @@ namespace DiscordChatExporter.Core.Models
 
         public override string ToString() => $"{GetLargestWholeNumberValue():0.##} {GetLargestWholeNumberSymbol()}";
     }
+
+    public partial struct FileSize
+    {
+        public static FileSize FromBytes(long bytes) => new FileSize(bytes);
+    }
 }

DiscordChatExporter.Core.Models/Member.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Linq;
 
 namespace DiscordChatExporter.Core.Models
 {