forms/BaseObservationFormSet: Add missing initialization of member variable (W0201)

Fixes the attribute-defined-outside-init (W0201) pylint error.

Signed-off-by: Fabian P. Schmidt <kerel@mailbox.org>

.pylintrc

@@ -10,5 +10,4 @@ disable=
     R0912, # too-many-branches
     R0913, # too-many-arguments
     R0914, # too-many-locals
-    W0201, # attribute-defined-outside-init
     W0703, # broad-except

.pylintrc3

@@ -12,5 +12,4 @@ disable=
     R0912, # too-many-branches
     R0913, # too-many-arguments
     R0914, # too-many-locals
-    W0201, # attribute-defined-outside-init
     W0703, # broad-except

network/base/forms.py

@@ -81,6 +81,8 @@ class ObservationForm(forms.ModelForm):
 
 class BaseObservationFormSet(forms.BaseFormSet):
     """Base FormSet class for Observation objects forms"""
+    transmitters = {}
+
     def __init__(self, user, *args, **kwargs):
         """Initializes Observation FormSet"""
         self.user = user