style(742): ruff format the new tests with the CI-pinned version

CI's 'Script lint and tests' went red on `ruff format --check`. `ruff check` was clean and
the suite was green throughout — this was purely formatting of lines this branch added, and
it is a gap in MY local gate: I ran pytest and the decisions validator every round and never
ran the formatter.

Formatted with ruff 0.12.11, the version pr-checks.yml pins, rather than the local install —
the pin exists precisely so the verdict is not a function of whoever ran it, and a different
version could have reformatted lines this branch never touched. The diff is confined to
blocks added here (a re.subn call, two assertion strings, two parametrize entries).

Verified over the whole CI population, not just the file I edited:
git ls-files '*.py' | xargs ruff check   -> All checks passed
git ls-files '*.py' | xargs ruff format --check -> 43 files already formatted

scripts/tests: 1012 passed, 2 skipped.

scripts/tests/test_pr_changed_files.py

@@ -1339,8 +1339,12 @@ def _run_classify(
         # against a multi-entry value. Every other test runs the singleton `timothy`, under which a
         # loop that can only ever match its LAST entry is indistinguishable from a correct one — and
         # the workflow's own diagnostic tells operators to add a second entry.
-        body, n = re.subn(r'^(\s*)H10_REVIEWERS="[^"]*"$', lambda m: f'{m.group(1)}H10_REVIEWERS="{reviewers}"',
-                          body, flags=re.MULTILINE)
+        body, n = re.subn(
+            r'^(\s*)H10_REVIEWERS="[^"]*"$',
+            lambda m: f'{m.group(1)}H10_REVIEWERS="{reviewers}"',
+            body,
+            flags=re.MULTILINE,
+        )
         assert n == 1, f"expected exactly one H10_REVIEWERS assignment to override, substituted {n}"
     script.write_text(body)
     r = subprocess.run(["bash", str(script)], cwd=tmp_path, env=env, capture_output=True, text=True)
@@ -1763,8 +1767,7 @@ def test_a_verdict_shaped_SUCCESS_from_a_NON_allowlisted_account_is_RE_DERIVED(t
     # reaches, not on a separate annotation: the annotation that used to carry this was withdrawn
     # after cold review measured that deleting it left the whole suite green.
     assert creator in r.stdout, (
-        "the diagnostic does not name the account whose verdict was discarded. "
-        f"Log:\n{r.stdout[-1200:]}"
+        f"the diagnostic does not name the account whose verdict was discarded. Log:\n{r.stdout[-1200:]}"
     )
     # The VALUE, not the word. An earlier draft asserted `"H10_REVIEWERS" in stdout`, which the
     # remediation sentence satisfies on its own — so deleting the allow-list from the diagnostic left
@@ -2042,11 +2045,9 @@ def test_an_account_on_NEITHER_entry_is_still_re_derived(tmp_path):
 @pytest.mark.parametrize(
     "shape,creator,desc",
     [
-        ("a null creator (an Actions-token write)", None,
-         "Review-verdict: BLOCKED @ a9e3e23 (base: main)"),
+        ("a null creator (an Actions-token write)", None, "Review-verdict: BLOCKED @ a9e3e23 (base: main)"),
         ("a description that is not a verdict", "timothy", "blocked by hand"),
-        ("a verdict recorded against ANOTHER base", "timothy",
-         "Review-verdict: BLOCKED @ a9e3e23 (base: other)"),
+        ("a verdict recorded against ANOTHER base", "timothy", "Review-verdict: BLOCKED @ a9e3e23 (base: other)"),
     ],
 )
 def test_an_UNATTRIBUTABLE_failure_is_still_RE_DERIVED(tmp_path, shape, creator, desc):