Standardize the shebang line of python scripts to using /usr/bin/env, which was already the vastly dominant choice

src/filters/kosplitter.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #################################
 # Copyright (C) 2020 J.F.Dockes
 #   This program is free software; you can redistribute it and/or modify

src/filters/rclepub

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 """Extract Html content from an EPUB file (.epub)"""
 from __future__ import print_function
 

src/filters/rclhwp.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 # Copyright (C) 2020 J.F.Dockes
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by

src/filters/rclpst.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #################################
 # Copyright (C) 2019 J.F.Dockes
 #   This program is free software; you can redistribute it and/or modify

src/filters/rclpython.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 # Rclpython is based on "colorize.py" from:
 # http://chrisarndt.de/en/software/python/colorize.html