Run however you're comfortable.
For me, that is shirtless 99.9% of the time. I hate the feeling of something hanging off me so it's either a tighter fitting shirt or shirtless. I feel like more of a dumbA wearing my trisuit singlet coming off a brick workout than I do running shirtless.
Who gives a flying F what others think? If they are judging you, that is their problem, not yours. We don't wear shirts at the pool, the beach, the lake, etc so why does it matter on a run? If someone gets offended by the sight of a male chest or a female with a sports bra, they can jump right back to the 1910's for all I care.