[bugfix] fixed import for tukey in newer scipy versions

pylot/core/pick/charfuns.py

@@ -17,7 +17,11 @@ autoregressive prediction: application ot local and regional distances, Geophys.
 :author: MAGS2 EP3 working group
 """
 import numpy as np
-from scipy import signal
+try:
+    from scipy.signal import tukey
+except ImportError:
+    from scipy.signal.windows import tukey
+
 from obspy.core import Stream
 
 from pylot.core.pick.utils import PickingFailedException