feat(A005): support detecting a shadowing folder

[asfaltboy]

Package directories that are named the same as built-in modules can also cause the issue. This should handle both:

Given a directory with these files:

❯ eza -T temp/
drwxr-xr-x - asfaltboy  8 Apr 13:44  temp
drwxr-xr-x - asfaltboy  8 Apr 13:44 ├──  typing
.rw-r--r-- 0 asfaltboy  8 Apr 13:44 │  └──  __init__.py
.rw-r--r-- 0 asfaltboy 20 Feb 11:22 ├──  __init__.py
.rw-r--r-- 9 asfaltboy 19 Feb 14:57 └──  logging.py

Running flake8 with the plugin on this PR's branch, results in:

❯ flake8 ./temp/
./temp/logging.py:0:1: A005 the module is shadowing a Python builtin module "logging"
./temp/typing/__init__.py:0:1: A005 the module is shadowing a Python builtin module "typing"

fix #124

[gforcada]

Thanks! 🤩

Would you mind adding a change log entry? I will make a release right away then 😄

[gforcada]

@asfaltboy thanks!! 🤗