upgrade Asciidoctor Tabs, the Antora Gradle plugin, and Node.js

build.gradle

@@ -1,6 +1,10 @@
 plugins {
 	id 'base'
-	id 'org.antora' version '1.0.0-alpha.5'
+	id 'org.antora' version '1.0.0-alpha.7'
+}
+
+node {
+	version = '19.4.0'
 }
 
 antora {
@@ -14,7 +18,7 @@ antora {
 	dependencies = [
 		'@antora/atlas-extension': '1.0.0-alpha.1',
 		'@antora/collector-extension': '1.0.0-alpha.3',
-		'@asciidoctor/tabs': '1.0.0-alpha.11',
+		'@asciidoctor/tabs': '1.0.0-alpha.12',
 		'@opendevise/antora-release-line-extension': '1.0.0-alpha.2',
 		'@springio/antora-extensions': '1.0.0-alpha.2',
 		'@springio/asciidoctor-extensions': '1.0.0-alpha.8',

lib/antora/templates/per-branch-antora-playbook.yml

@@ -1,4 +1,4 @@
-# PACKAGES antora@3.2.0-alpha.2 @antora/collector-extension@1.0.0-alpha.3 @springio/antora-extensions@1.0.0-alpha.2 @asciidoctor/tabs@1.0.0-alpha.11
+# PACKAGES antora@3.2.0-alpha.2 @antora/collector-extension@1.0.0-alpha.3 @springio/antora-extensions@1.0.0-alpha.2 @asciidoctor/tabs@1.0.0-alpha.12
 #
 # The purpose of this Antora playbook is to build the docs in the current branch.
 antora: