Flag constants fix

• adresses #495 and fixes issue
• adds reported bug as test case

saqc/funcs/constants.py

@@ -74,9 +74,7 @@ class ConstantsMixin:
         rolling = d.rolling(window=window, min_periods=min_periods)
         starting_points_mask = rolling.max() - rolling.min() <= thresh
 
-        starting_points_mask = removeRollingRamps(
-            starting_points_mask, window=window, inplace=True
-        )
+        starting_points_mask = removeRollingRamps(starting_points_mask, window=window)
 
         # mimic forward rolling by roll over inverse [::-1]
         rolling = starting_points_mask[::-1].rolling(