Changes to Get scite journal index for multiple ISSNs

the response property additionalProperties/items/issns became optional for the status 200

the response property additionalProperties/items/journalSlug became optional for the status 200

response property additionalProperties/items/relativeYear list-of-types was widened by adding types null to media type application/json of response 200

response property additionalProperties/items/sjiAllYears list-of-types was widened by adding types null to media type application/json of response 200

response property additionalProperties/items/sjiFiveYears list-of-types was widened by adding types null to media type application/json of response 200

response property additionalProperties/items/sjiTwoYears list-of-types was widened by adding types null to media type application/json of response 200