Update get other costs

[Kariamos]

This pull request adds a required cost field to the "other costs" API and ensures that several fields are now required in both the OpenAPI specification and the TypeScript types. It also updates the backend logic and tests to include and validate the new cost field for each item.

API and Schema Updates:

• Made items a required property in the response schema for the relevant endpoint in openapi.yml, and marked several fields (including cost, cost_id, type, supplier, description, attachments) as required for each item. [1] [2]
• Added the cost field as a required number property for each cost item in both the OpenAPI schema and the generated TypeScript types, and updated the response examples accordingly. [1] [2] [3]

Backend and Type Updates:

• Updated the OtherCost type and the backend route handler to include and return the new cost field for each cost item. [1] [2] [3]

Test Updates:

• Updated tests to expect the cost field in all relevant assertions for returned cost items. [1] [2] [3] [4] [5]

Other Schema Improvements:

• Marked name and id as required for nested type and supplier objects, and made id, url, and mimetype required for attachments. [1] [2] [3]

[github-actions]

Tests difference: