Fix uploads from mobile clients (and dep updates)

This patch fixes the file upload send by the mobile clients.
It resolves #2644 by always providing a `Content-Type` even though one
isn't set in this specific case.

I do hope it will be fixed upstream by either Bitwarden by fixing the
client. Or Rocket by allowing to override this somehow.

Until then, we can use this patched version of multer-rs.

Issue @ Rocket: https://github.com/SergioBenitez/Rocket/issues/2299
Issue @ Bitwarden: https://github.com/bitwarden/mobile/issues/2018

Also updated some dependencies.