plugin: linter: add ruff to default configuration.

[ghost]

Hi,
Just adding ruff to the micro linter plugin configuration.

[Andriamanitra]

I think this is a great addition. ruff has become one of the standard tools for linting and formatting Python code so it makes sense to add it as one of the default linters.

[JoeKar]

Seems to be a good moment to synchronize the doc again to the default list present in the linter.lua:
https://github.com/zyedidia/micro/blob/b432bb7cfafa9a1c07acdf28eba8eb87c67b6793/runtime/plugins/linter/help/linter.md?plain=1#L8-L25
😉

[JoeKar]

Am I right, that we execute on a pure default setup every available linter per filetype match in a row?
https://github.com/zyedidia/micro/blob/b432bb7cfafa9a1c07acdf28eba8eb87c67b6793/runtime/plugins/linter/linter.lua#L131-L139

Should we add a check to stop after the first successful execution and on top of that should we add a priority for more than one available linter in the default list/map?