add shebang to voice track scripts

scripts/cut-voice-track.py

@@ -1,3 +1,4 @@
+#! /usr/bin/env python
 # pip install -r requirements.txt
 usage = 'python cut-voice-track.py <?wav timestamp json> <?wav filename>'
 

scripts/transcribe-voice-track.py

@@ -1,3 +1,4 @@
+#! /usr/bin/env python
 # pip install -r requirements.txt
 usage = 'python transcribe-voice-track.py <?wav filename>'