deps: Upgrade Electron to v21.0.1

[taratatach]

Please make sure the following boxes are checked:

• [x] PR is not too big
• [x] it improves UX & DX in some way
• [ ] it includes unit tests matching the implementation changes
• [x] it includes scenarios matching a new behaviour or has been manually tested
• [x] it includes relevant documentation

[taratatach]

Closing in favor of https://github.com/cozy-labs/cozy-desktop/pull/2279