Prepare release v30.0.4

- drawio submodule: unchanged (no drawio_ref supplied; CI builds from drawio-dev) (88ee1f5ab4d40603a8f3aaa0d9d6dc3794c6b3f0)
- Updated package.json version to 30.0.4
- Updated package-lock.json
- Electron version: 42.3.0

Automated by prepare-release workflow