I have the following regex `^(2[0-3]|1?[0-9])?(\:[0-5]?[0-9])?$`

`8:45` matches, however `08:45` does not.

How can this be re-written to also allow `08:45`?

---

I would also like like to check for either the `.` or `:` if possible instead of just the `.`