Update wordpress/wordpress-importer requirement from ^0.8 to ^0.9

Updates the requirements on wordpress/wordpress-importer to permit the latest version.

---
updated-dependencies:
- dependency-name: wordpress/wordpress-importer
  dependency-version: 0.9.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -15,7 +15,7 @@
         "wp-cli/wp-cli": "^2.12"
     },
     "require-dev": {
-        "wordpress/wordpress-importer": "^0.8",
+        "wordpress/wordpress-importer": "^0.9",
         "wp-cli/entity-command": "^1.3 || ^2",
         "wp-cli/export-command": "^1 || ^2",
         "wp-cli/extension-command": "^1.2 || ^2",