datetimes and dates are not substitutable

[asukaminato0721]

Describe the Bug

ref astral-sh/ty#615

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEmqALjExDTHe8bpUw8xgAaASzYcAOuikQwo1uxiF0uAO4AKAJR0APPMJNcjUlsRS6FusUoR0TdRJBMAFswDkcOqjpwArpWsIOBgAQkdNECEQMkoYMChSA1ooCgBiOgAFUlj40h8MHAI6AGNcdEgAc39mCDLCKXSAZRhOZyYmYjhEAHpumLiEwl4K7ph0bsxcYrhu0vKIKsoasu66MF4vADdUaFRsWBKyyuq2MrpcYlP0OHr0MhcygFpNmEo4WvQ6AF46RwBmQgARgATI4pABtV7UN4AXSkvnQ3F4LEwj0wEFixTYL2%2BdDcCxUsTcUhUTEesQAjr4MTBUQBrGCkR6oYrFeCeH5uVSoSjoYnoEAAXyiLOxMAAYtAYBQ0Fg8EQyEKgA

(Only applicable for extension issues) IDE Information

No response