Ignore pyflakes F401 'Module imported but unused' for __init__.py only

Be more specific rather than globally enabling the exception. Documentation at https://flakeheaven.readthedocs.io/en/latest/config.html#example

pyproject.toml

@@ -16,7 +16,10 @@ show_source = true
 
 [tool.flakeheaven.plugins]
 pycodestyle = ["+*", "-E501", "-W503"]
-pyflakes = ["+*", "-F401"]
+pyflakes = ["+*"]
+
+[tool.flakeheaven.exceptions."**/__init__.py"]
+pyflakes = ["-F401"]
 
 [tool.pytest.ini_options]
 minversion = "6.0"