Add a .rpm release to the release file #45

Using a crate called cargo-rpm we can easily create a .rpm package for our project which should later be added to the release files. Bare in mind that a new testing CI job will be required to make sure it's working.

Related to:

• Add an arch release to the release file #44
• Add a .deb release to the release file #42
• Add an a-pack release file (package format for Alpine) #51

Blocked by:

• Add release cycle workflows #31