How to upload multiple files in bulk?

## What is your question?
I'm looking for a way to upload about 100 files at once in bulk.

## Versions
* **What version of the SDK are you using?**
`^10.7.0` (latest)

## Additional context
I'm currently having an array of about 100 files that I loop over every day.
In each loop, I fetch those files and upload the latest version to Dropbox using the `filesUpload` method.

I however have to retry uploading already quite fast because I get `429: Too Many Requests` errors.
Therefore I use the `retry_after` to set as the delay, but since I'm uploading that many files at once, I keep getting those errors.

All these files are smaller than the 150MB file size limit.

I would like to find a way to upload all these files in batch, without having to retry the upload all the time.

Thanks in advance for your help!