demo: modify shebang to call Python through /usr/bin/env

.gitignore

@@ -5,3 +5,4 @@
 /build/
 /dist/
 /re6stnet.egg-info/
+.idea
\ No newline at end of file

demo/demo

-#!/usr/bin/python
+#!/usr/bin/env python3
 import argparse, math, nemu, os, re, signal
 import socket, sqlite3, subprocess, sys, time, weakref
 from collections import defaultdict

demo/py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 def __file__():
     import argparse, os, sys
     sys.dont_write_bytecode = True

re6st/tests/test_unit/test_registry.py

@@ -397,7 +397,7 @@ class TestRegistryServer(unittest.TestCase):
 
         self.assertEqual(get_hmac(), [None, key_2, key_1])
 
-        #setp 5
+        # step 5
         self.server.updateHMAC()
 
         self.assertEqual(get_hmac(), [key_2, None, None])