import re

s = str({1:'тест'})

def hex2dec(s):
	return int(s[2:], 16)

a = re.findall(r'\\...', s)
b = map(hex2dec,a)

for i in zip(a,b):
	s = s.replace(i[0], chr(i[1]))
	
f=open('C:\\temp\\news.txt','w')
f.write(s)
f.close()