Changes to Get scite journal index for ISSN

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

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

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

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

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

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

query request parameter year list-of-types was widened by adding types null

for the query request parameter year, the type was generalized from string to no type