Update boto3 to support AWS EC2 IMDSv2

[rodrigost23]

Issue Summary

I'm trying to use the (apparently undocumented) ATHENA_ASSUME_ROLE option, but Redash uses an old boto3 version (< 1.11.0), which does not support IMDSv2: https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide//use-a-supported-sdk-version-for-imdsv2.html

Steps to Reproduce

1. Setup an EC2 on AWS with IMDS v2-only
2. Try to use "assume role" in an Athena Data Source
3. Get a "credentials not found" error

IMDSv2 is more secure and should work when using EC2 on AWS. Upgrading boto3 to 1.12.6 would be enough.

[rodrigost23]

Apparently this has been addressed in #6207

[justinclift]

Ahhh yep. That was a few days ago. We're very actively updating our old dependencies presently, as well as going through the list of PRs and merging/closing things as makes sense. 😄

[shuklaabhi]

Lets close this PR

[guidopetri]

Thanks for pointing out that this is done @shuklaabhi :)