fix: package.json & package-lock.json to reduce vulnerabilities (#28)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ACTIONSCORE-2980270

Author: snyk-bot

package-lock.json

@@ -20,7 +20,7 @@
   },
   "homepage": "https://github.com/stefanbuck/github-issue-parser#readme",
   "dependencies": {
-    "@actions/core": "^1.2.6",
+    "@actions/core": "^1.9.1",
     "js-yaml": "^4.0.0"
   },
   "devDependencies": {