Bump @oclif/core from 1.9.0 to 2.9.1

Bumps [@oclif/core](https://github.com/oclif/core) from 1.9.0 to 2.9.1.
- [Release notes](https://github.com/oclif/core/releases)
- [Changelog](https://github.com/oclif/core/blob/main/CHANGELOG.md)
- [Commits](oclif/core@v1.9.0...2.9.1)

---
updated-dependencies:
- dependency-name: "@oclif/core"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

package.json

@@ -7,7 +7,7 @@
   },
   "bugs": "https://github.com/keisuke6065/openapi-combine/issues",
   "dependencies": {
-    "@oclif/core": "^1",
+    "@oclif/core": "^2",
     "@oclif/plugin-help": "^5",
     "@oclif/plugin-plugins": "^2.0.1",
     "@types/js-yaml": "^4.0.5",