chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     if: startsWith(github.ref, 'refs/tags/') != true
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: astral-sh/setup-uv@v7
       - run: uv run --frozen pyright
       - run: uv run --frozen ruff check
@@ -26,7 +26,7 @@ jobs:
       id-token: write
       contents: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - uses: astral-sh/setup-uv@v7