Update sonogram.py

sonogram.py

@@ -232,6 +232,9 @@ class Sonogram():
             duration = 0
             tracking = False
             for stepClass,timeIncrement,members in zip(timeStepClass,st,timeStepMembers):
+                # Check for case of exact end of audio
+                if st == maxTime:
+                    continue
                 if stepClass == c:
                     if currMembers == members: