Remove `/usr/bin/env python` lines where appropriate

[diazona]

Discussed in #29

^{Originally posted by rominf March 3, 2022}

pytest-localserver/pytest_localserver/plugin.py

Line 1 in bebb98b

#!/usr/bin/env python

is useless since there is nothing except fixtures in the file.

I'm not sure about this:

pytest-localserver/pytest_localserver/smtp.py

Line 1 in bebb98b

#!/usr/bin/env python

since there is a code:

pytest-localserver/pytest_localserver/smtp.py

Lines 101 to 122 in bebb98b

	if __name__ == "__main__": # pragma: no cover
	import time
	server = Server()
	server.start()
	print('SMTP server is running on %s:%i' % server.addr)
	print('Type <Ctrl-C> to stop')
	try:
	try:
	while True:
	time.sleep(1)
	finally:
	print('\rstopping...')
	server.stop()
	except KeyboardInterrupt:
	# support for Python 2.4 dictates that try ... finally is not used
	# together with any except statements
	pass

but it's ancient; not sure if someone still uses it.