Bump @springio/antora-zip-contents-collector-extension in /antora

Bumps [@springio/antora-zip-contents-collector-extension](https://github.com/spring-io/antora-zip-contents-collector-extension) from 1.0.0-alpha.8 to 1.0.0-alpha.9.
- [Commits](spring-io/antora-zip-contents-collector-extension@v1.0.0-alpha.8...v1.0.0-alpha.9)

---
updated-dependencies:
- dependency-name: "@springio/antora-zip-contents-collector-extension"
  dependency-version: 1.0.0-alpha.9
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

antora/package-lock.json

@@ -9,7 +9,7 @@
     "@antora/atlas-extension": "1.0.0-alpha.5",
     "@springio/antora-extensions": "1.14.7",
     "@springio/antora-xref-extension": "1.0.0-alpha.4",
-    "@springio/antora-zip-contents-collector-extension": "1.0.0-alpha.8",
+    "@springio/antora-zip-contents-collector-extension": "1.0.0-alpha.9",
     "@asciidoctor/tabs": "1.0.0-beta.6",
     "@springio/asciidoctor-extensions": "1.0.0-alpha.17",
     "patch-package": "^8.0.1"