feat: support deepin OS

[SteveLauC]

Standards checklist:

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself
  • I also tested that Topgrade skips the step where needed

If you developed a feature or a bug fix for someone else and you do not have the
means to test it, please tag this person here.

What does this PR do

Support deepin Linux, it is a distro based on debian. In its /etc/os-release file, there is no ID_LIKE field so topgrade can not fall back to debian in the current impl.

# before
$ topgrade --dry-run --only system
Error detecting current distribution: Unknown Linux Distribution

# after
$ topgrade --dry-run --only system
── 13:21:35 - System update ────────────────────────────────────────────────────
Dry running: /usr/bin/sudo apt-get update
Dry running: /usr/bin/sudo apt-get dist-upgrade

── 13:21:35 - Summary ──────────────────────────────────────────────────────────
System update: OK