[python] Fix shebangs to use the "right" interpreter. (#3292)

Co-authored-by: Fabien-B <Fabien-B@github.com>

doc/sphinx/source/tutorials/interfacing_with_paparazzi.rst

@@ -28,7 +28,7 @@ This python example shows the reception and emission of messages. For the recept
 .. code-block:: python
     :linenos:
 
-    #!/usr/bin/python3
+    #!/usr/bin/env python3
     import sys
     import time
     import os