Checkout base repo for changelog

The changelog tool was checking out the branch repo. This was done
to enable pushing, but since the tool no longer pushes, it's not
necessary.

.changes/tool/amend.py

@@ -71,13 +71,20 @@ def amend(
 
 def get_new_changes(base: str | None) -> dict[Path, Change]:
     base = base or os.environ.get("GITHUB_BASE_REF", "main")
-    print(f"Running a diff against base branch: {base}")
-    result = subprocess.run(
-        f"git diff origin/{base} --name-only",
-        check=True,
-        shell=True,
-        capture_output=True,
-    )
+    print(f"Running a diff against base branch: `{base}`")
+
+    try:
+        result = subprocess.run(
+            f"git diff --name-only origin/{base}",
+            check=True,
+            shell=True,
+            capture_output=True,
+        )
+    except subprocess.CalledProcessError as e:
+        print(f"stdout: {e.stdout.decode("utf-8")}\n\nstderr: {e.stderr.decode("utf-i")}")
+        raise
+
+    print(f"Changed files:\n{result.stdout.decode("utf-8")}")
 
     new_changes: dict[Path, Change] = {}
     for changed_file in result.stdout.decode("utf-8").splitlines():

.github/workflows/changelog-ci.yml

@@ -7,9 +7,6 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - uses: actions/checkout@v4
-              with:
-                ref: ${{ github.head_ref }}
-                repository: ${{ github.event.pull_request.head.repo.full_name }}
 
             - uses: actions/setup-python@v5
               with: