fix: packages/backend-test-utils/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

packages/backend-test-utils/package.json

@@ -42,11 +42,11 @@
     "start": "backstage-cli package start"
   },
   "dependencies": {
-    "@backstage/backend-app-api": "workspace:^",
+    "@backstage/backend-app-api": "0.5.0",
     "@backstage/backend-common": "workspace:^",
-    "@backstage/backend-plugin-api": "workspace:^",
-    "@backstage/config": "workspace:^",
-    "@backstage/plugin-auth-node": "workspace:^",
+    "@backstage/backend-plugin-api": "0.6.19",
+    "@backstage/config": "0.1.1",
+    "@backstage/plugin-auth-node": "0.6.0",
     "@backstage/types": "workspace:^",
     "better-sqlite3": "^8.0.0",
     "express": "^4.17.1",