fix: Canonical URL needs : and / unescaped

Author: fsbraun

djangocms_frontend/templates/djangocms_frontend.html

@@ -12,7 +12,7 @@
                 <meta property="og:description" content="{% page_attribute meta_description %}"/>
             {% endblock meta %}
             {% block canonical_url %}
-                <link rel="canonical" href="{{ request.build_absolute_uri|urlencode:"&?" }}"/>
+                <link rel="canonical" href="{{ request.build_absolute_uri|urlencode:":/&?" }}"/>
                 <meta property="og:url" content="{{ request.build_absolute_uri|urlencode:"&?" }}"/>
             {% endblock canonical_url %}
             {% block fb_meta %}{% endblock fb_meta %}