date-time regex allows timezone offset to be missing

[bredelman]

I'm using this library in tandem with oapi codegen. I am validating a request with ?start_time\=2024-10-22T00:00:00-04:00 as a query param. The validation works fine but I was experimenting and removed the timezone offset and sent ?start_time\=2024-10-22T00:00:00 and that seems to make it past the validation from kin openapi and doesn't make it past the codegen generated validation for date-time.

In their library they do

// Time is a special case of a struct that we handle
			parsedTime, err := time.Parse(time.RFC3339Nano, src)
			if err != nil {
				parsedTime, err = time.Parse(types.DateFormat, src)
				if err != nil {
					return fmt.Errorf("error parsing '%s' as RFC3339 or 2006-01-02 time: %s", src, err)
				}
			}

time.Parse, so if I'm understanding this right, I think the regex needs to be strengthened to match that validation