Upgrade boto to boto3

`boto` has created issues in `tubular` repo. To avoid any breakage upgrade it to boto3.

This repo is also using [luigi](https://github.com/edx/luigi). But using via [hash](https://github.com/openedx/edx-analytics-pipeline/blob/c0981cf75bbc19ef5aec0369a3f930e9188480fb/requirements/default.txt#L9) its pretty old commit.