message: user-settings: remove duplicate core-plugin-api dependency
diff: "devDependencies": {
  "@backstage/cli": "^0.8.1",
  "@backstage/core-app-api": "^0.1.19",
  - "@backstage/core-plugin-api": "^0.1.11",
  "@backstage/dev-utils": "^0.2.12",
  "@backstage/test-utils": "^0.1.20",
  "@testing-library/jest-dom": "^5.10.1",
  