bug: time_input failing with parsed dates

[rmm-ch]

We use a st.time_input element to define the timestamp of the input image.
If the image has no valid metadata, the user has to define the time.

For reasons I do not yet understand, creating a legitimate datetime object by parsing a legitimate string works for the st.date_input but not for the time_input.

date_value = datetime.datetime.strptime(image_datetime, '%Y:%m:%d %H:%M:%S').date()
time_value = datetime.datetime.strptime(image_datetime, '%Y:%m:%d %H:%M:%S').time()

found when working on fix for #16, not a quick fix so raising new issue.