Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

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

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Install Python
       uses: actions/setup-python@v6
       with:
@@ -41,7 +41,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Install Python
       uses: actions/setup-python@v6
       with:
@@ -61,7 +61,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Install Python
       uses: actions/setup-python@v6
       with:
@@ -81,7 +81,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Install Python
       uses: actions/setup-python@v6
       with:
@@ -101,7 +101,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Install Python
       uses: actions/setup-python@v6
       with:
@@ -122,7 +122,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Set up QEMU
       uses: docker/setup-qemu-action@v3
     - name: 🧰 Set up Docker Buildx
@@ -147,7 +147,7 @@ jobs:
       id-token: write
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 📥 Download Python wheels
       uses: actions/download-artifact@v4
       with:
@@ -170,7 +170,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 🧰 Set up QEMU
       uses: docker/setup-qemu-action@v3
     - name: 🧰 Set up Docker Buildx
@@ -211,7 +211,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: 📥 Download Python wheels
       uses: actions/download-artifact@v4
       with: