Bump @electron-forge/maker-flatpak from 6.4.2 to 7.4.0

Bumps [@electron-forge/maker-flatpak](https://github.com/electron/forge) from 6.4.2 to 7.4.0.
- [Release notes](https://github.com/electron/forge/releases)
- [Changelog](https://github.com/electron/forge/blob/main/CHANGELOG.md)
- [Commits](https://github.com/electron/forge/compare/v6.4.2...v7.4.0)

---
updated-dependencies:
- dependency-name: "@electron-forge/maker-flatpak"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -21,7 +21,7 @@
   "devDependencies": {
     "@electron-forge/cli": "^6.0.5",
     "@electron-forge/maker-deb": "^6.0.5",
-    "@electron-forge/maker-flatpak": "^6.0.5",
+    "@electron-forge/maker-flatpak": "^7.4.0",
     "@electron-forge/maker-rpm": "^6.0.5",
     "@electron-forge/maker-squirrel": "^6.0.5",
     "@electron-forge/maker-zip": "^6.0.5",