Cannot upgrade to latest versions of httpoison,certifi,idna,hackney.

[himanshu0128]

After installing gcloudex and goth, i had to run mix deps.get again which downgraded several dependencies.

• httposion 0.12.0 -> 0.8.3
• certifi 1.2.1 -> 1.0.0
• hackney 1.8.6 -> 1.6.6
• idna 5.0.2 -> 4.0.0

Update gcloudex to use newer versions if these deps.

[aandr]

I'd also add Poison to the list. GCloudex requires 1.2 or 2.1, current is 3.1.

[dsignr]

I believe @sashaafm wasn't able to do it because Goth internally used Httpoison 0.xx. I just raised an issue on Goth as well and @peburrows was kind enough to respond and address the issue.