Make mypy (type hints) happy

@Property, its setter and @AbstractMethod
do not work well together in mypy.
This fix was suggested in a GitHub issue:
python/mypy#4165

src/alldecays/data_handling/abstract_data_set.py

@@ -23,46 +23,56 @@ def decay_names(self):
         pass
 
     @decay_names.setter
-    @abstractmethod
     def decay_names(self, new_names):
-        pass
+        # See: https://github.com/python/mypy/issues/4165
+        # Since we can't also decorate this with abstract method we want to be
+        # sure that the setter doesn't actually get used as a noop.
+        raise NotImplementedError
 
     @property
     @abstractmethod
     def data_brs(self):
         pass
 
     @data_brs.setter
-    @abstractmethod
     def data_brs(self, new_names):
-        pass
+        # See: https://github.com/python/mypy/issues/4165
+        # Since we can't also decorate this with abstract method we want to be
+        # sure that the setter doesn't actually get used as a noop.
+        raise NotImplementedError
 
     @property
     @abstractmethod
     def fit_start_brs(self):
         pass
 
     @fit_start_brs.setter
-    @abstractmethod
     def fit_start_brs(self, new_names):
-        pass
+        # See: https://github.com/python/mypy/issues/4165
+        # Since we can't also decorate this with abstract method we want to be
+        # sure that the setter doesn't actually get used as a noop.
+        raise NotImplementedError
 
     @property
     @abstractmethod
     def luminosity_ifb(self):
         pass
 
     @luminosity_ifb.setter
-    @abstractmethod
     def luminosity_ifb(self, new_names):
-        pass
+        # See: https://github.com/python/mypy/issues/4165
+        # Since we can't also decorate this with abstract method we want to be
+        # sure that the setter doesn't actually get used as a noop.
+        raise NotImplementedError
 
     @property
     @abstractmethod
     def signal_scaler(self):
         pass
 
     @signal_scaler.setter
-    @abstractmethod
     def signal_scaler(self, new_names):
-        pass
+        # See: https://github.com/python/mypy/issues/4165
+        # Since we can't also decorate this with abstract method we want to be
+        # sure that the setter doesn't actually get used as a noop.
+        raise NotImplementedError