Ecto 3 and other dependency updates

[SachsKaylee]

Hello there!

This library looks very promising. However I am currently unable to install it because some dependencies and child dependencies are rather out of date causing a mismatch with my versions. Most notable is the missing support for Ecto 3 and an old version of HTTPPosion. (I'd also love to be able to use Poison for JSON instead of Jason, but this is not a priority for me)

I've already forked all three repos in question for me (exille, exfile_b2 & b2_client) but I currently lack the knowledge and time to fully update all of them, espeically since I am just getting started with Backblaze & Exfile and experimenting around with it.

For this reason I'd like to kindly ask if there are any plans on updating the dependencies to never minor & major versions?

Thank you for your time