templates: change wording for password change (fixes #22225)

src/authentic2/templates/registration/password_change_form.html

@@ -13,9 +13,13 @@
 
 {% block content %}
   <form method="post" action=".">
+    {% if user.has_usable_password %}
     <p>{% blocktrans %}To change your password you must provide your current password, then provide
     the new password and confirm it.
     {% endblocktrans %}</p>
+    {% else %}
+    <p>{% blocktrans %}You are going to define your account password.{% endblocktrans %}</p>
+    {% endif %}
     {% csrf_token %}
     {{ form.as_p }}
     <button class="submit-button">{% trans 'Submit' %}</button>