Use bash and python3 from env

etc/ppp/ip-down.local.example

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 case "$PPP_IPPARAM" in
     openfortivpn*)

etc/ppp/ip-up.local.example

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 case "$PPP_IPPARAM" in
     openfortivpn*)

tests/lint/astyle.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Copyright (c) 2015 Adrien Vergé
 
 # Check that astyle is installed

tests/lint/checkpatch.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Copyright (c) 2020 Dimitri Papadopoulos
 
 # Path to checkpatch.pl

tests/lint/eol-at-eof.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Copyright (c) 2015 Adrien Vergé
 
 rc=0

tests/lint/line_length.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 # Copyright (c) 2015 Adrien Vergé
 
 """Enforce maximum line length in openfortivpn C source code.

tests/lint/run.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Copyright (c) 2015 Adrien Vergé
 
 rc=0