fix(scm): correctly check hostnames for repo URL generation

[ErichDonGubler]

Regressed by #393 (CC @padenot as the author of that PR). Prompted by bug 1999127, comment 8 from @tomrittervg.

[ErichDonGubler]

@tomrittervg: Just pushed up another fix that I think is uncontroversial (CC @padenot).

[ErichDonGubler]

NOTE: I have not fully tested this, because I'm unfamiliar with how to do so here. The change seemed simple enough, and I've run this locally to make sure the new hostname check snippet itself works:

def is_chromium(repo: str) -> bool:
    return any(
        hostname in repo
        for hostname in [
            "https://chromium.googlesource.com",
            "https://aomedia.googlesource.com",
        ]
    )
    
assert is_chromium("https://chromium.googlesource.com")
assert is_chromium("https://aomedia.googlesource.com")
assert not is_chromium("https://github.com")
assert not is_chromium("https://gitlab.com")