Dynamic content in tag attributes for calendar links

[husseinalhammad]

Hard-coding the from and to values work fine:

<perch:sharing id="google_cal" title="Perch CMS workshop" from="2019-04-02 09:00" to="2019-04-02 10:00">

However, a common use-case would be to use a start and an end date/time (e.g. for an event):

<perch:content id="title" type="text" label="Title" required>
<perch:content id="event_start_date_time" type="date" time required>
<perch:content id="event_end_date_time" type="date" time required>

<perch:sharing id="google_cal" title="{title}" from="{start_date_time}" to="{end_date_time}">

However, the above does not work at the moment (v2.0.2) and results in an error.