[Bug]: Task3 post fails

[the-shtorm]

Brief problem description

implementation of task3 post request fails due to code 500 internal server error

in learner class default value of enrolled_at must be changed from None to datetime.now() or something to make default value of enrolled at not None

DB sends error with null value in enrolled_at cell during learner addition

Steps to Reproduce

• implement POST method for learners
• rebuild app
• send POST /learners
• find error

Expected Result

code 201 successful new learner

Actual Result

code 500 internal server error