pmb: Use unpacking operator to concatenate collections (MR 2525)

See https://docs.astral.sh/ruff/rules/collection-literal-concatenation

This is also slightly faster according to a microbenchmark that
shows it taking around 19% less time to run:
https://github.com/astral-sh/ruff/pull/1957#issue-1538092351

pmb/helpers/repo_missing.py

@@ -82,7 +82,7 @@ def generate(arch: Arch) -> list[dict[str, list[str] | str | None]]:
 
             # Add abuild to depends if needed
             if pkgname != "abuild" and is_abuild_forked(repo):
-                depends = ["abuild"] + depends
+                depends = ["abuild", *depends]
 
             depends = sorted(depends)