misc: drop compatibility with django-select2 < 5 (#35569)

Version 5 was released in 2015.

bijoe/visualization/forms.py

@@ -24,18 +24,7 @@ from django.utils.safestring import mark_safe
 from django.forms import ModelForm, TextInput, NullBooleanField
 from django.conf import settings
 
-try:
-    from django_select2.forms import Select2MultipleWidget
-
-    def build_select2_multiple_widget():
-        return Select2MultipleWidget()
-
-except ImportError:
-    from django_select2.widgets import Select2MultipleWidget
-
-    def build_select2_multiple_widget():
-        return Select2MultipleWidget(select2_options={'width': '100%'})
-
+from django_select2.forms import Select2MultipleWidget
 
 from . import models
 
@@ -203,7 +192,7 @@ class CubeForm(forms.Form):
                     choices=[(s, label) for v, s, label in members],
                     coerce=coercion_function(members),
                     required=False,
-                    widget=build_select2_multiple_widget())
+                    widget=Select2MultipleWidget())
 
         # group by
         self.base_fields['drilldown_x'] = forms.ChoiceField(