Fix code scanning alert - Overly permissive regular expression range

[cvzi]

mensa/util.py

Line 22 in eef62fe

restricted_chars = re.compile('[^\u0009\u000A\000D\u0020-\uD7FF\uE000-\uFFFD\u10000-\u10FFFF]')

Tracking issue for:

• https://github.com/cvzi/mensa/security/code-scanning/2