Update CI runners to Ubuntu 22.04 and remove workaround for qemu.

[sengi]

Description of the change

Update the GitHub Actions CI runners from Ubuntu 20.04 to 22.04 and remove the workaround for installing a new enough version of qemu. The version of qemu that comes with Ubuntu 22.04 is new enough that we no longer need that workaround.

CI builds and pushes to DockerHub succeed with this change.

Fixes #132. Builds were failing because the CI job was trying to install qemu from the Ubuntu Hirsute repo, which reached end-of-life and was finally deleted last month. The errors looked like:

E: The repository 'http://archive.ubuntu.com/ubuntu hirsute Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu hirsute-updates Release' does not have a Release file.
E: The repository 'http://security.ubuntu.com/ubuntu hirsute-security Release' does not have a Release file.
Error: Process completed with exit code 100.

Tested by running the CI workflow on the forked repo, with the docker repo BASENAME monkeypatched to point at my DockerHub account so that the GitHub Actions jobs have permissions to push to DockerHub without running on the Bitnami GitHub repo. The monkeypatch commit is only on the default branch of the forked repo, not on this PR's branch.

Possible drawbacks

I'm not aware of any drawbacks to this yet, but please let me know if I've missed something.

Applicable issues

132

[sengi]

Force-pushed to add Signed-off-by lines for DCO check.

[sengi]

Friendly ping :) Hope you folks are all ok. peace and love ❤️‍🩹

[sengi]

Thanks, @aruiz14!