version information regex: adjust 

https://www.flake8rules.com/rules/W605.html

> As of Python 3.6, a backslash-character pair that is not a valid escape sequence now generates a DeprecationWarning. This will eventually become a SyntaxError.


better:

```
version = re.search(
    r'^__version__\s*=\s*"(.*)"', open("...").read(), re.M
).group(1)
```