fix: plugins/stack-overflow/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AJV-15274295
- https://snyk.io/vuln/SNYK-JS-QS-15268416

Author: snyk-io[bot]

plugins/stack-overflow/package.json

@@ -27,15 +27,15 @@
     "@backstage/core-plugin-api": "workspace:^",
     "@backstage/plugin-home-react": "workspace:^",
     "@backstage/plugin-search-common": "workspace:^",
-    "@backstage/plugin-search-react": "workspace:^",
-    "@backstage/theme": "workspace:^",
+    "@backstage/plugin-search-react": "0.1.0",
+    "@backstage/theme": "0.1.1",
     "@material-ui/core": "^4.12.2",
     "@material-ui/icons": "^4.9.1",
     "@testing-library/jest-dom": "^5.10.1",
     "@types/react": "^16.13.1 || ^17.0.0",
     "cross-fetch": "^3.1.5",
     "lodash": "^4.17.21",
-    "qs": "^6.9.4",
+    "qs": "^6.14.2",
     "react-use": "^17.2.4"
   },
   "peerDependencies": {