fix: plugins/kafka/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-DIFF-14917201
- https://snyk.io/vuln/SNYK-JS-TAR-15032660

Author: snyk-io[bot]

plugins/kafka/package.json

@@ -26,8 +26,8 @@
   "dependencies": {
     "@backstage/catalog-model": "workspace:^",
     "@backstage/config": "workspace:^",
-    "@backstage/core-components": "workspace:^",
-    "@backstage/core-plugin-api": "workspace:^",
+    "@backstage/core-components": "0.8.6",
+    "@backstage/core-plugin-api": "0.1.0",
     "@backstage/plugin-catalog-react": "workspace:^",
     "@backstage/theme": "workspace:^",
     "@material-ui/core": "^4.12.2",