fix: plugins/events-backend-module-gerrit/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-TAR-15032660
- https://snyk.io/vuln/SNYK-JS-TAR-15127355
- https://snyk.io/vuln/SNYK-JS-ESLINT-15102420

Author: snyk-bot

plugins/events-backend-module-gerrit/package.json

@@ -35,8 +35,8 @@
     "postpack": "backstage-cli package postpack"
   },
   "dependencies": {
-    "@backstage/backend-plugin-api": "workspace:^",
-    "@backstage/plugin-events-node": "workspace:^",
+    "@backstage/backend-plugin-api": "0.6.19",
+    "@backstage/plugin-events-node": "0.2.9",
     "winston": "^3.2.1"
   },
   "devDependencies": {