workflows-build: Fail to build packages in PR

[outloudvi]

Currently the workflow cannot build PRs: Sample log for #4224.

Long story long, read this GitHub blog.

Long story short:

• Git v2.35.2 workarounds CVE-2022-24765 by safe.directory.
• actions/checkout workarounds safe.directory by creating user-wide .gitconfig (this config doesn't work in repo-wide .gitconfig) - that's why it worked.
• To avoid flushing .gitconfig on self-hosted runners, actions/checkout uses a temporary home directory to put user .gitconfig.
• gh CLI apparently isn't aware of that temporary .gitconfig - that's why it failed.

The most simple solution: set user-wide actions/checkout in the runner - we don't use self-hosted runners for now on aosc-os-abbs.

The simple and robust solution: use actions/checkout to check out PRs.

See-Also: actions/checkout#762

[outloudvi]

cc @KexyBiscuit for vis - which method (or other solution) would you recommend?