Unable to create VPKs over 4GB in size

[newgreenshoot]

I was looking to use this tool for my project. We have a large number of assets, with our materials alone surpassing 6GB. I used the CLI tool to attempt to create a VPK from a folder, and received this error after the file had surpassed 4GB in size:

Traceback (most recent call last):
  File "/home/ccormier/.local/bin/vpk", line 8, in <module>
    sys.exit(main())
  File "/home/ccormier/.local/lib/python3.10/site-packages/vpk/cli.py", line 207, in main
    run(args)
  File "/home/ccormier/.local/lib/python3.10/site-packages/vpk/cli.py", line 171, in run
    create_vpk(args)
  File "/home/ccormier/.local/lib/python3.10/site-packages/vpk/cli.py", line 166, in create_vpk
    new_vpk.save(args.file)
  File "/home/ccormier/.local/lib/python3.10/site-packages/vpk/__init__.py", line 162, in save
    f.write(struct.pack("IHHIIH", checksum & 0xFFffFFff,
struct.error: 'I' format requires 0 <= number <= 4294967295

If this is a strict format limitation, it'd probably be better to not attempt VPK creation and instead warn the user.