Hide requirements field in AK submission form if no requirements are modelled for the event

This implements #199

AKSubmission/forms.py

@@ -62,6 +62,8 @@ class AKForm(AvailabilitiesFormMixin, forms.ModelForm):
 
         self.fields['category'].queryset = AKCategory.objects.filter(event=self.initial.get('event'))
         self.fields['requirements'].queryset = AKRequirement.objects.filter(event=self.initial.get('event'))
+        if self.fields['requirements'].queryset.count() == 0:
+            self.fields['requirements'].widget = forms.HiddenInput()
         self.fields['prerequisites'].queryset = AK.objects.filter(event=self.initial.get('event')).exclude(
             pk=self.instance.pk)
         self.fields['conflicts'].queryset = AK.objects.filter(event=self.initial.get('event')).exclude(