Bug#958775: lintian-brush: Update package-uses-deprecated-debhelper-compat-version.py fixer to handle compat 9->10 and 12->13

[Niels Thykier]

Jelmer Vernooij:
> Hi Niels,
> 
> [...]
> 
> A minor thing that would help is if there was some way to get the
> latest stable debhelper compat version, i.e. something like
> Debian::Debhelper::Dh_Lib::LOWEST_NON_DEPRECATED_COMPAT_LEVEL but that
> was currently set to 13.
> 
> Cheers,
> 
> Jelmer
> 

I have added a HIGHEST_STABLE_COMPAT_LEVEL to Debian::Debhelper::Dh_Lib,
which will be available from the next upload. :)

~Niels