Bump actions/checkout from 5 to 6 in the actions group

Bumps the actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/benchmark.yml

@@ -18,7 +18,7 @@ jobs:
     name: Benchmarks
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install poetry
         run: pipx install poetry
       - name: Set up Python 🐍

.github/workflows/pypi.yml

@@ -15,7 +15,7 @@ jobs:
     permissions:
       id-token: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install poetry
         run: pipx install poetry
       - name: Set up Python 🐍

.github/workflows/unittester.yml

@@ -14,7 +14,7 @@ jobs:
     name: 🔬 Test (🐍 ${{ inputs.python-version }})
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install poetry
         run: pipx install poetry
       - name: Set up Python ${{ inputs.python-version }} 🐍