[INFRANG-7651] escape json string for atlantis workflow

[jakegut]

Clever Coding Standards Agreement

• Author and Review Statement, "We agree this code adheres to our Clever Global Coding Standards and other applicable Coding Standards"

JIRA

https://clever.atlassian.net/browse/INFRANG-7651

About

• if there's a ' within the github event, it'll result in an error as demonstrated here as the JSON isn't properly escaped
• Set the data as an env var to let bash handle the proper escaping

Checklist

• [n.a] Increment the version number in VERSION
• [n.a] Add release notes

Testing

• tested in this pr https://github.com/Clever/tf-atlantis-test/pull/3