Lift trait bounds from #[debug(skip)] fields (#281)

[tyranron]

Resolves #281

Synopsis

See #281:

struct NoDebug;
                                     
#[derive(derive_more::Debug)]
struct HasDebug<T>(#[debug(skip)] T);
                                     
dbg!(HasDebug(NoDebug));

I'd be fine with needing to manually specify something like #[debug(bounds())].

Solution

Fix how ignore/skip attributes are considered in bounding of derive(Debug) macro.

Checklist

• Documentation is updated (not required)
• Tests are added/updated
• CHANGELOG entry is added (not required)

[ModProg]

should there be a test case for a custom field format?

[tyranron]

@ModProg done.