Bump electron from 11.5.0 to 15.5.5 in /20.10/elec-demo

Bumps [electron](https://github.com/electron/electron) from 11.5.0 to 15.5.5.
- [Release notes](https://github.com/electron/electron/releases)
- [Changelog](https://github.com/electron/electron/blob/main/docs/breaking-changes.md)
- [Commits](electron/electron@v11.5.0...v15.5.5)

---
updated-dependencies:
- dependency-name: electron
  dependency-type: direct:development
...

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Author: dependabot[bot]