Resolve some hugo warnings

[Phemisters]

When I run hugo locally I see a variety of warnings - it would be good to reduce these.

WARN  deprecated: project config key languages.pt_br.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.pt_br.label instead.
WARN  deprecated: project config key languages.nl.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.nl.label instead.
WARN  deprecated: project config key languages.fr.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.fr.label instead.
WARN  deprecated: project config key languages.en.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.en.label instead.
WARN  deprecated: project config key languages.de.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.de.label instead.
WARN  deprecated: project config key languages.gl.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.gl.label instead.
WARN  deprecated: project config key languages.eo.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.eo.label instead.
WARN  deprecated: project config key languages.pl.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.pl.label instead.
WARN  deprecated: project config key languages.it.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.it.label instead.
WARN  deprecated: project config key languages.uk.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.uk.label instead.
WARN  deprecated: project config key languages.es.languageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use languages.es.label instead.
...
WARN  deprecated: css.Sass: libsass was deprecated in Hugo v0.153.0 and will be removed in a future release. Use dartsass instead. See https://gohugo.io/functions/css/sass/#dart-sass
WARN  deprecated: .Language.LanguageCode was deprecated in Hugo v0.158.0 and will be removed in a future release. Use .Language.Locale instead.
WARN  Raw HTML omitted while rendering "/home/david/Projects/dtdocs/content/_index.md"; see https://gohugo.io/getting-started/configuration-markup/#rendererunsafe
You can suppress this warning by adding the following to your project configuration:
ignoreLogs = ['warning-goldmark-raw-html']
WARN  deprecated: .Language.LanguageName was deprecated in Hugo v0.158.0 and will be removed in a future release. Use .Language.Label instead.
WARN  Raw HTML omitted while rendering "/home/david/Projects/dtdocs/content/darkroom/masking-and-blending/overview.md"; see https://gohugo.io/getting-started/configuration-markup/#rendererunsafe

[Phemisters]

I've been doing some experiments, but it is going slowly. Many things in package.json are out-of-date, but updating them tends to expose other deprecated features. I plan to keep working on this in the background.