upgrade build to Antora 3.0.0-alpha.4

[mojavelinux]

No description provided.

[mojavelinux]

The AsciiDoc quick reference is impacted by this bug in Asciidoctor: asciidoctor/asciidoctor#4023

We could apply a workaround or wait until the next release of Asciidoctor/Asciidoctor.js is available.

[mojavelinux]

We're also getting a new warning about a missing attribute reference in the content source for Asciidoctor EPUB3. This is either a regression in Asciidoctor 2, or Asciidoctor 2 is reporting a missing attribute where it didn't before.

Update: It looks like an unintended side effect of a fix. See asciidoctor/asciidoctor#4024

[mojavelinux]

We're going to wait on Antora 3.0.0-alpha.4 to upgrade.

[mojavelinux]

The changes are now very minor. The impact is as follows:

• Listing blocks with no style are promoted to a source block if the source-language is set (generally only affects listing blocks in the asciidoc component)
• Space in mailto link is represented as + instead of %20
• Normal substitutions are applied to cells in table header row if column has a (asciidoc) or l (literal) style
• table-frame and table-grid attributes apply to nested tables
• Remove extensions that backport Asciidoctor 2 features (collapsible block and global table frame and grid attributes)