CI: Update CircleCI config.

[mejiaj]

Description

Resolves CircleCI build failures. Updates ruby in docker image to 2.6 → 2.7 in.circleci/config.yml. It's latest LTS release before 3.0 [efe4ab5]

Additional information

⚠ Note

• We should add ffi to our Gemfile in the future if this pops again
• Sometimes CircleCI will fail on npm run test:detached because it takes too long. In this case we should restart from failed until we look at potential options of speeding up CircleCI tasks

Other updates

• Setting bundle path via config since --path flag will be deprecated soon [d88613a]
• Consistent quotes in Gemfile [a1b1eed]
• Upated Snyk and ran Snyk wizard [b2cceff] and [628390b]

Before you hit Submit, make sure you’ve done whichever of these applies to you:

• Follow the 18F Front End Coding Style Guide and Accessibility Guide.
• Run npm test and make sure the tests for the files you have changed have passed.
• Run your code through HTML_CodeSniffer and make sure it’s error free.
• Title your pull request using this format: [Website] - [UI component]: Brief statement describing what this pull request solves.

[mejiaj]

@thisisdano can you test this in ruby 2.6 (our current setup) and then again on 2.7? Just want to be sure this works on both. Locally I've switched to 2.7.

[thisisdano]

Excellent. Thank you!