Hackney version needs updated to fix HTTPS key retrieval

[jonryser]

Related: benoitc/hackney#591

The fix has been in the Hackney code for a couple of days, but an actual release was just made. Proposing we update the version dependency in mix.exs to read {:hackney, "~> 1.15.2"}.

[ltj]

Created PR #9

[victorolinasc]

Thanks for your PR! I'll take a closer look at it in a moment.

Just to note that you can override the dep with {:hackney, "~> 1.15.2", override: true} in your mix.exs. That should work too without a new release.

I will, of course, bump the dep once I get the time to test it properly.

Thanks a lot for letting us know about the issue on hackney!

[victorolinasc]

There was not much to test :)

Thanks again for your PR @ltj