fix(tests): correct assertion in excluded hours test

[kyonlee]

The test_get_excluded_hours_for_crontab_tasks method had assertions for excluded hours that could fail depending on the test execution time. We can only guarantee what hours are not returned by test_get_excluded_hours_for_crontab_tasks and have amended the test to do so.

[kyonlee]

When the test is executed on the 2nd or 6th hour, the assertions checking now_hour + 2 and now_hour - 2 are in excluded_hours will fail respectively, because "4" and "04" are always removed from excluded_hours.

I have removed these assertions and have added one to verify that "4" and "04" is not in excluded_hours.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.73%. Comparing base (a70a9dc) to head (7f4b987).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #858      +/-   ##
==========================================
+ Coverage   87.42%   87.73%   +0.31%     
==========================================
  Files          32       32              
  Lines         954      954              
  Branches       76       76              
==========================================
+ Hits          834      837       +3     
+ Misses        102      100       -2     
+ Partials       18       17       -1     

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