Create a random number with Liquid for Customer Testimonials Metaobject

random_number.liquid

{% comment %}
  my_reviews is an array of metaobjects assigned via metafields
{% endcomment %}

{% liquid 
  assign review_min = 1
  assign review_max = my_reviews.size
  assign mod_ref = review_max | minus: review_min
  assign random_number = "now" | date: "%N" | modulo: mod_ref | plus: review_min
  assign review = my_reviews[random_number]
%}