Add older runners

[adriens]

❔ Context

Actually we only test on runs-on: ubuntu-latest and as the aim of this tool is to support legacy systems it could be interesting to run on olds OS

🎯 Actions

Add the following to the CI :

• `ubuntu-20.04``
• ⚠️ ubuntu-18.04 DEPRECATED ⚠️
• Merger les PRs en cours
• releaser

🔖 Resources

• https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources
• GitHub Actions: The Ubuntu 18.04 Actions runner image is being deprecated and will be removed by 12/1/22