S3-Store: the info file is created but never updated

[matthias-tn]

Describe the bug
I'm using tusd (v2.8.0) with an S3 storage backend. I'm using the .info file to read details about uploads. Unfortunately it seems that the .info file is only created when a new upload is created and never uploaded when the upload is finished (e.g. Offset is always 0).

To Reproduce
Steps to reproduce the behavior:

1. Setup tusd with an S3 storage
2. Start upload
3. Open the corresponding .info file and check the "Offset" after the first parts are uploaded -> it is 0
4. Open the corresponding .info file and check the "Offset" after the upload completed -> it is 0

Expected behavior
The .info file is updated when a file part/chunk was uploaded and when a S3 multipart upload finished, to ensure that the "Size" and the "Offset" within the .info file match after a file was completely uploaded

Setup details
Please provide following details, if applicable to your situation:

• Used tusd version: 2.8.0
• Used tusd data storage: AWS S3
• Used tus client library: [e.g. tus-js-client, Uppy.js]