Fix spaces_get_occupancy_schedule floating point math

[eringold]

Pull request overview

Fixes occupancy schedule regression due to imprecise math causing occupancy threshold to not be met, and the 'test_hvac_psz_split_from_mz' PRM regression test to fail.

Pull Request Author

• [x] Method changes or additions
• [ ] Data changes or additions
• [x] Added tests for added methods
• [ ] If methods have been deprecated, update rest of code to use the new methods
• [ ] Documented new methods using yard syntax
• [ ] Resolved yard documentation errors for new code (ran bundle exec rake doc)
• [ ] Resolved rubocop syntax errors for new code (ran bundle exec rake rubocop)
• [x] All new and existing tests passes
• [ ] If the code adds new require statements, ensure these are in core ruby or add to the gemspec

Review Checklist

This will not be exhaustively relevant to every PR.

• [x] Perform a code review on GitHub
• [x] All related changes have been implemented: method additions, changes, tests
• [x] Check rubocop errors
• [x] Check yard doc errors
• [x] If fixing a defect, verify by running develop branch and reproducing defect, then running PR and reproducing fix
• [ ] If a new feature, test the new feature and try creative ways to break it
• [x] CI status: all green or justified