Updated shebangs to be more portable

scripts/addInfos.py

-#! /usr/bin/python3
+#! /usr/bin/env python3
 
 import sys
 

scripts/conllu2fplm.py

-#! /usr/bin/python3
+#! /usr/bin/env python3
 
 import sys
 from readMCD import readMCD

scripts/conllu2splits.py

-#! /usr/bin/python3
+#! /usr/bin/env python3
 
 import sys
 from readMCD import readMCD

scripts/conlluCheckProblems.py

-#! /usr/bin/python3
+#! /usr/bin/env python3
 
 import sys
 

scripts/extractMachines.py

-#! /usr/bin/python3
+#! /usr/bin/env python3
 
 import sys
 import os