Don't modify powerprofilesctl at build time

Python version and binary used at build time might not be the same
as the installed OS.  Instead reference python3 from environment.

src/meson.build

@@ -98,20 +98,11 @@ executable('power-profiles-daemon',
   install_dir: libexecdir
 )
 
-python = import('python')
-py_installation = python.find_installation('python3', required: true)
-
-ppd_conf = configuration_data()
-ppd_conf.set('VERSION', meson.project_version())
-ppd_conf.set('PYTHON3', py_installation.full_path())
-
-script = configure_file(
-  input: 'powerprofilesctl.in',
-  output: 'powerprofilesctl',
-  configuration: ppd_conf,
-  install_dir: get_option('bindir')
+script = 'powerprofilesctl'
+install_data(script,
+             install_dir: get_option('bindir')
 )
-
+script = join_paths(meson.current_source_dir(), script)
 if get_option('pylint')
   test('pylint-powerprofilesctl',
        pylint,

src/powerprofilesctl

@@ -1,12 +1,10 @@
-#!@PYTHON3@
+#!/usr/bin/env python3
 
 import signal
 import subprocess
 import sys
 from gi.repository import Gio, GLib
 
-VERSION = "@VERSION@"
-
 PP_NAME = "org.freedesktop.UPower.PowerProfiles"
 PP_PATH = "/org/freedesktop/UPower/PowerProfiles"
 PP_IFACE = "org.freedesktop.UPower.PowerProfiles"