Fix registration of plugin

[dopplershift]

According to the flake8 plugin docs, the entry point name should be the error code prefix that will be emitted from the plugin. Otherwise, apparently flake8 will silently discard messages. Fix that by registering under C801.

[dopplershift]

See for reference: http://flake8.pycqa.org/en/latest/plugin-development/registering-plugins.html

[peterjc]

Does this fix #10?

[dopplershift]

Possibly? Not sure what the root cause of #10 is.

[Paul-AUB]

Tested with flake8==3.9.1, it works.

Without this fix, you must specify select = C in the config file (and it didn't work with extend-select). It's really a bargain as it doesn't work the same way as every other plugins which defaultly select their error codes when installed. So in my project I would need to know and select manually every code of every plugin...

I am very interrested in this fix, would it be considered to have a release with it ? (I see last activity in 2019)

[toofar]

Looks like the plugin requires this change to work at all with flake 5.0, see PyCQA/flake8#325

I'm getting

There was a critical error during execution of Flake8:
plugin code for flake8-copyright[flake8_copyright] does not match ^[A-Z]{1,3}[0-9]{0,3}$