Update to Zola 0.22.1

[ElTh0r0]

While trying to update a docs page, I couldn't run zola serve, because the current config.toml wasn't compatible with newer zola versions. Output:

Building site...
ERROR Failed to serve the site
ERROR TOML parse error at line 39, column 1
   |
39 | highlight_code = true
   | ^^^^^^^^^^^^^^
unknown field `highlight_code`, expected one of `highlighting`, `render_emoji`, `external_links_class`, `external_links_target_blank`, `external_links_no_follow`, `external_links_no_referrer`, `external_links_external`, `smart_punctuation`, `definition_list`, `bottom_footnotes`, `lazy_async_image`, `insert_anchor_links`, `github_alerts`

With v0.22 the highlighting was changed, see zola changelog and I updated the config accordingly.

[mmahmoudian]

Thanks. Last week I stumbled upon this and I started fixing it, but the priorities changed and I it left unfinished. I'll compare your branch with mine and then merge this.