fix format function to handle pointer of time.Time

[KimMachineGun]

Summary

Since the time.Time implements fmt.Stringer interface, *time.Time was formatted with fmt.Stringer. To format it with formatTime, I added an explicit check for *time.Time.

Checklist

• Unit and integration tests covering the common scenarios were added

[CLAassistant]

All committers have signed the CLA.