message: fix(nextjs): Move `@sentry/webpack-plugin` back to non-dev dependencies
  This reverts the change made in The SDK user needs the webpack plugin in order to upload their sourcemaps, so it needs to be installed when they install the SDK.
diff: "@sentry/react": "6.12.0",
  "@sentry/tracing": "6.12.0",
  "@sentry/utils": "6.12.0",
  + "@sentry/webpack-plugin": "1.17.1",
  "tslib": "^1.9.3"
  },
  "devDependencies": {
  "@sentry/types": "6.12.0",
  - "@sentry/webpack-plugin": "1.17.1",
  "@types/webpack": "^5.28.0",
  "eslint": "7.20.0",
  "next": "10.1.3",
  