deps: explicit the @oclif/core dependency used in main.js

This commit explicits the dependency on @oclif/core (we use the Config
type from that lib in the main.js file) instead on relying on implicit
dependency (from the bump-cli package).

Author: paulRbr

package-lock.json

@@ -44,7 +44,8 @@
     "@actions/github": "^5.1.1",
     "@actions/io": "^1.1.3",
     "@octokit/types": "^14.1.0",
-    "bump-cli": "^2.10.0"
+    "bump-cli": "^2.10.0",
+    "@oclif/core": "^4.8.1"
   },
   "devDependencies": {
     "@github/local-action": "^5.1.0",