Bump serverless-webpack from 5.3.5 to 5.4.0 (#784)

Bumps [serverless-webpack](https://github.com/serverless-heaven/serverless-webpack) from 5.3.5 to 5.4.0.
- [Release notes](https://github.com/serverless-heaven/serverless-webpack/releases)
- [Changelog](https://github.com/serverless-heaven/serverless-webpack/blob/master/CHANGELOG.md)
- [Commits](serverless-heaven/serverless-webpack@v5.3.5...v5.4.0)

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