To help clarify why you are required to depreciate, even though you are renting it out for less than one year, take a look at IRS Publication 527 page 6, middle column. Under "Excepted Property" it states that you do not depreciate "Property placed in service and disposed of (or taken out of business use) in the same year." So your situation doesn't meet that requirement. You placed it in service in 2020, and will be selling the property (thus disposing of it) in the next tax year. So you're required to depreciate it.
