Close filestream in SendFile(filePath) after sending

src/Discord.Net/Models/Channel.cs

@@ -357,8 +357,11 @@ namespace Discord
             return msg;
         }
 
-        public Task<Message> SendFile(string filePath)
-            => SendFile(Path.GetFileName(filePath), File.OpenRead(filePath));
+        public async Task<Message> SendFile(string filePath)
+        { 
+            using (var stream = File.OpenRead(filePath))
+                return await SendFile(Path.GetFileName(filePath), stream);
+        }
         public async Task<Message> SendFile(string filename, Stream stream)
         {
             if (filename == null) throw new ArgumentNullException(nameof(filename));