ci: bump checkout@v5 + setup-python@v6 (Node 24)

GitHub forces Node 24 on Actions runners from June 2026 and removes
Node 20 in Sept 2026. actions/checkout@v4 and actions/setup-python@v5
run on Node 20 and logged deprecation warnings on the v0.3.0 publish.
Bump to the Node-24 majors. No behaviour change; pypa/gh-action-pypi-publish
is unaffected.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: tylnexttime

.github/workflows/ci.yml

@@ -18,10 +18,10 @@ jobs:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
 
@@ -52,8 +52,8 @@ jobs:
     permissions:
       id-token: write   # OIDC publishing — no PyPI token in repo secrets
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.12"
       - name: Build