<div class="input-group">
  {% include "django/forms/widgets/text.html" %}
  <span class="input-group-addon">{{ currency }}</span>
</div>

<div class="input-group">
  {% include "django/forms/widgets/text.html" %}
  <div class="input-group-append">
    <span class="input-group-text">{{ currency }}</span>
  </div>
</div>

Fix price widget input for Bootstrap 4
Fix price widget input for Bootstrap 4