Upgrade heroku stack to 24

[jazairi]

Bumps heroku stack from 22 to 24. I've tested the build process and GraphQL playground and haven't noticed any issues.

Developer

Ticket(s)

https://mitlibraries.atlassian.net/browse/TCO-47

Accessibility

• ANDI or Wave has been run in accordance to our guide and
  all issues introduced by these changes have been resolved or opened
  as new issues (link to those issues in the Pull Request details above)
• There are no accessibility implications to this change

Documentation

• Project documentation has been updated, and yard output previewed
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ENV

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Stakeholders

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Dependencies and migrations

YES dependencies are updated (sort of -- Heroku stack)

NO migrations are included

Reviewer

Code

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  added technical debt.

Documentation

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  (not just this pull request message).
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Testing

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