Updates format to be a single string

[JPrevost]

Why are these changes being introduced:

• This was a bug in the graphql spec. TIMDEX has always treated format as a single string

Relevant ticket(s):

• https://mitlibraries.atlassian.net/browse/GDT-151

How does this address that need:

• Updates GraphQL spec to correct the expectation to be a single string

Document any side effects to this change:

• None of the TIMDEX sources mapped to anything other than a single string for format. Therefore, anyone requesting format via GraphQL would be getting an error in production at this time. This resolves that problem, so a deprecation does not feel appropriate. This was a bug that caused the inability to use a field, not a change in how a previously usable field is being mapped.
• Even though the previous comment remains true, we'll still need to refresh the spec in our deployed timdex ui instances as the spec has indeed changed.

Developer

• All new ENV is documented in README
• All new ENV has been added to Heroku Pipeline, Staging and Prod
• 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)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer

• The commit message is clear and follows our guidelines
  (not just this pull request message)
• There are appropriate tests covering any new functionality
• The documentation has been updated or is unnecessary
• The changes have been verified
• New dependencies are appropriate or there were no changes

Requires database migrations?

NO

Includes new or updated dependencies?

NO

[jazairi]

I'm not getting any errors requesting format when testing this locally, but it's returning null for that field for seemingly every record. Do you have a sample search I can use to verify this that will return a record with a format?

[ghukill]

I'm not getting any errors requesting format when testing this locally, but it's returning null for that field for seemingly every record. Do you have a sample search I can use to verify this that will return a record with a format?

I don't know if helpful, but in Dev1 the record gismit:EG_CAIRO_A25TOPO_1972 should have a value. This graphql query for this record in Dev1 currently throws a 500.

I believe the ticket had another link from @JPrevost that showed this works now, but I'm a little fuzzy on which Heroku URLs are pointing at which Opensearch instances (and it looks like that link no longer works).

[ghukill]

I read the change as going from an array of strings to a single string, which makes sense to me given that the TIMDEX data model in Transmogrifier for the format field will always write a single string or nothing.