Use package.json for package management

Issue gh-14819

build.gradle

@@ -11,12 +11,4 @@ antora {
 		'ALGOLIA_APP_ID': 'WB1FQYI187',
 		'ALGOLIA_INDEX_NAME': 'springdocs',
 	]
-	// NOTE remember to update the versions in lib/antora/templates/per-branch-antora-playbook.yml as well
-	dependencies = [
-		'@antora/atlas-extension': '1.0.0-alpha.1',
-		'@antora/collector-extension': '1.0.0-alpha.3',
-		'@asciidoctor/tabs': '1.0.0-beta.3',
-		'@springio/antora-extensions': '1.7.0',
-		'@springio/asciidoctor-extensions': '1.0.0-alpha.8',
-	]
 }

package.json

@@ -0,0 +1,10 @@
+{
+  "dependencies": {
+    "antora": "latest",
+    "@antora/atlas-extension": "1.0.0-alpha.1",
+    "@antora/collector-extension": "1.0.0-alpha.3",
+    "@asciidoctor/tabs": "1.0.0-beta.3",
+    "@springio/antora-extensions": "1.7.0",
+    "@springio/asciidoctor-extensions": "1.0.0-alpha.8"
+  }
+}