Update actions/checkout action to v6 (#37)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
     timeout-minutes: 25
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python }}

.github/workflows/publish_release.yml

@@ -21,7 +21,7 @@ jobs:
       contents: write
       id-token: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
         with:
           version: latest