fix: handle the case when required checks is disabled

[peterzcc]

what

Check if the optional field RequiredStatusChecks in the response is nil, and return a success early if "Require status checks to pass before merging" is disabled

why

tests

references

closes #2663

[peterzcc]

@nitrocode could I have a review?

[jamengual]

We will try to review soon

[peterzcc]

pending the testing fix from #3653

[chenrui333]

refresh the latest changes

[chenrui333]

@peterzcc can you add tests for the change? Thanks!

[peterzcc]

@chenrui333 The tests turns out to be non-trivial with the absence of ListCheckRunsCheckSuite mocking in existing tests. While this change is a trivial fix to handle the nil pointer case which would happen when Require status checks to pass before merging is disabled.

[GenPage]

Looks like this was already merged in #3672 Got confused, but it was the merge commit update that caused it.