`TableOfContent` shows incorrect page number when footer margin pushes `Header` to the next page in `MultiPage`

[DetachHead]

Describe the bug

To Reproduce Code snippet to reproduce the behavior:

import 'dart:io';

import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart' as pw;

void main() async {
  final file = File('asdf.pdf');
  final pdf = await (pw.Document(pageMode: PdfPageMode.outlines)
        ..addPage(
          pw.Page(
            build: (final context) {
              return pw.Column(
                children: [pw.TableOfContent()],
              );
            },
          ),
        )
        ..addPage(
          pw.MultiPage(
            footer: (final pw.Context context) {
              return pw.Container(
                margin: const pw.EdgeInsets.only(top: 1.0 * PdfPageFormat.cm),
                child: pw.Text(
                  'Page ${context.pageNumber} of ${context.pagesCount}',
                ),
              );
            },
            build: (final context) => [
              pw.Header(text: 'a', level: 1),
              pw.Text(pw.LoremText().paragraph(600)),
              pw.Header(text: 'b', level: 1),
            ],
          ),
        ))
      .save();
  await file.writeAsBytes(pdf);
}

Expected behavior

table of contents says "a" is on page 2 and "b" is on page 3

Screenshots

Flutter Doctor

[√] Flutter (Channel stable, 3.0.4, on Microsoft Windows [Version 10.0.19044.1826], locale en-AU)
[√] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Build Tools 2019 16.8.3)
[!] Android Studio (not installed)
[√] IntelliJ IDEA Community Edition (version 2019.2)
[√] IntelliJ IDEA Ultimate Edition (version 2022.1)
[√] IntelliJ IDEA Ultimate Edition (version 2022.2)
[√] VS Code, 64-bit edition (version 1.65.2)
[√] Connected device (4 available)
[√] HTTP Host Availability

Desktop (please complete the following information):

• [X] iOS
• [X] Android
• [ ] Browser
• [X] Windows
• [ ] Linux

Smartphone (please complete the following information):

• Device: iPhone 13
• OS: 15.1.1
• Browser safari
• Version idk