Removed explicit header addition

Author: serber

src/AspNet.Security.OAuth.VisualStudio/VisualStudioAuthenticationHandler.cs

@@ -72,9 +72,6 @@ protected override async Task<OAuthTokenResponse> ExchangeCodeAsync([NotNull] OA
 
         using var request = new HttpRequestMessage(HttpMethod.Post, Options.TokenEndpoint);
 
-        // TODO Review whether this is just a copy-paste mistake and is redundant by testing with a real instance
-        request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));
-
         request.Content = new FormUrlEncodedContent(tokenRequestParameters);
 
         using var response = await Backchannel.SendAsync(request, Context.RequestAborted);