Bump @antora/atlas-extension from 1.0.0-alpha.1 to 1.0.0-alpha.2

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

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -1,7 +1,7 @@
 {
   "dependencies": {
     "antora": "latest",
-    "@antora/atlas-extension": "1.0.0-alpha.1",
+    "@antora/atlas-extension": "1.0.0-alpha.2",
     "@antora/collector-extension": "1.0.0-alpha.3",
     "@asciidoctor/tabs": "1.0.0-beta.6",
     "@springio/antora-extensions": "1.7.0",