feat: add rpm artifacts

[altanunsal]

Adds RPM artifacts to build

CircleCI on my fork generated the artifacts https://app.circleci.com/pipelines/github/altanunsal/pocket-casts-desktop-app/4/workflows/55f88095-c99a-45ff-b8b1-77c233e42b56

Key changes

• Add @electron-forge/maker-rpm as a dev dependency
• Update the ci config to include the rpm package in the docker image so rpmbuild cli is available for electron-forge
• Add some additional config

TODO

Consider creating a rpm repository via COPR: https://docs.fedoraproject.org/en-US/quick-docs/publish-rpm-on-copr/

[altanunsal]

Relates to #34

@felicianotech let me know if you need any additional info / feedback etc.

[FelicianoTech]

@altanunsal Apologies for the delay. If you're still interested, if you can just do a rebase. The package.json file and the lock file in particular will likely need conflicts fixed.

[FelicianoTech]

Closing due to lack of response.