Bump @antora/collector-extension in /docs (#1406)

---
updated-dependencies:
- dependency-name: "@antora/collector-extension"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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docs/package.json

@@ -2,7 +2,7 @@
   "dependencies": {
     "antora": "3.2.0-alpha.6",
     "@antora/atlas-extension": "1.0.0-alpha.2",
-    "@antora/collector-extension": "1.0.0-beta.2",
+    "@antora/collector-extension": "1.0.0-beta.3",
     "@asciidoctor/tabs": "1.0.0-beta.6",
     "@springio/antora-extensions": "1.14.2",
     "@springio/asciidoctor-extensions": "1.0.0-alpha.14"