Update flatpak dependencies to non-EOL versions

[eaglesemanation]

Scope

electron-builder defaults to 20.08 version of flatpak runtime and base packages. Those packages are EOL, here is example message from flatpak cli:

Info: runtime org.freedesktop.Platform branch 20.08 is end-of-life, with reason:
   org.freedesktop.Platform 20.08 is no longer receiving fixes and security updates. Please update to a supported runtime version.

I couldn't really find a source of truth for those messages, I suspect it just part of flatpak repository that can report if package is EOL

Implementation

Manually specify versions for both runtime and base package. This will require to manually bump them later on, but it's just 2 lines of code change approximately every 2 years, so I hope that's not an issue =)

Screenshots

before	after

How to Test

Try building flatpak package on a linux distro with npm run publish:flatpak

Emoji Guide

For reviewers: Emojis can be added to comments to call out blocking versus non-blocking feedback.

E.g: Praise, minor suggestions, or clarifying questions that don’t block merging the PR.

🟢 Nice refactor!

🟡 Why was the default value removed?

E.g: Blocking feedback must be addressed before merging.

🔴 This change will break something important

Blocking	🔴 ❌ 🚨	RED
Non-blocking	🟡 💡 🤔 💭	Yellow, thinking, etc
Praise	🟢 💚 😍 👍 🙌	Green, hearts, positive emojis, etc

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[silentrald]

@eaglesemanation Seems to be good, could build and run the flatpak on my system.

@Zagrios could merge this PR. No workflow changes as well.

[Zagrios]

Seems good to me 🙌

[Zagrios]

Thanks a lot @eaglesemanation ! ❤️
Thanks @silentrald for the review 🙌
Merging 🚀