Fix partial update for sprint should use POST

[marcotollini]

Partial updates should use POST instead of PUT: https://docs.atlassian.com/jira-software/REST/9.17.0/#agile/1.0/sprint-partiallyUpdateSprint

[studioj]

did you encounter issues? just wonderingas our tests dont really show failures with putting

[marcotollini]

@studioj , yes, with PUT Jira Data Center is expecting you to define all the fields. Instead, with POST I can only define the fields that I intend to change

[studioj]

@marcotollini can you then add a test so that the two behaviors become apparent?

Thank you