fix: bump go-w3up, check content headers

[dtbuchholz]

Summary

Bumps go-w3up and also makes the change it implements here.

Details

• Note: even though we use go 1.21 and the error described by the w3s team happens with go 1.22, this seems to fix things.
• The content-length check is all we need, and things work without updating to go-w3up v0.0.3...but we might as well bump it since it doesn't affect the behavior. If needed, we can remove the dep update and use go-w3up v0.0.2, and things will work.

How it was tested

• Tried bumping to go-w3up v0.0.3, and I still received an empty server response, with the server logging this error:

   failed archiving CAR: status code: 403
  

• Made the recommend check in rcpt.Out().Ok().Headers.Values for the content-length, and then uploading random / new files worked:

  {
     "root": "bafybeihx5mvoz7vdnjevt4724mpwm5eh6mhqrle22axx2yx4haast4dlli", 
     "shard": "bagbaiera64rrqwenr7gmw6g2q6r4uchk36nobfnhg2362e6ujsfqoryzntcq"
  }

[carsonfarmer]

Hero!