Bump electron-updater from 6.3.4 to 6.3.9

Bumps [electron-updater](https://github.com/electron-userland/electron-builder/tree/HEAD/packages/electron-updater) from 6.3.4 to 6.3.9.
- [Release notes](https://github.com/electron-userland/electron-builder/releases)
- [Changelog](https://github.com/electron-userland/electron-builder/blob/master/packages/electron-updater/CHANGELOG.md)
- [Commits](https://github.com/electron-userland/electron-builder/commits/[email protected]/packages/electron-updater)

---
updated-dependencies:
- dependency-name: electron-updater
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>