chore(deps): bump actions/checkout from 5 to 6 (#427)

Bumps [actions/checkout](https://github.com/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
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -19,7 +19,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v6
         with:
@@ -42,7 +42,7 @@ jobs:
   check-docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v6
         with:
@@ -64,7 +64,7 @@ jobs:
         python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"]
         os: ["ubuntu-latest", "macos-14", "windows-latest"]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v6
         with:
@@ -92,7 +92,7 @@ jobs:
           - os: windows-latest
             architecture: aarch64
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - name: Set Rust target
         id: target
@@ -121,7 +121,7 @@ jobs:
   check-sdist-build:
     runs-on: "ubuntu-latest"
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - name: build sdist
         uses: PyO3/maturin-action@v1

.github/workflows/docs.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           # Fetch all branches
           fetch-depth: 0

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
         python-version: ["3.10", "3.14t"]
         architecture: [x86-64, aarch64]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - uses: actions/setup-python@v6
       with:
@@ -39,7 +39,7 @@ jobs:
         python-version: ["3.10", "3.14t"]
         architecture: [x86-64, aarch64]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - uses: actions/setup-python@v6
       with:
@@ -63,7 +63,7 @@ jobs:
         # amd64 only for windows, as no arm64 runners are available
         python-version: ["3.10", "3.14t"]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - uses: actions/setup-python@v6
       with:
@@ -82,7 +82,7 @@ jobs:
   sdist:
     runs-on: "ubuntu-latest"
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - uses: actions/setup-python@v6
         with:
@@ -109,7 +109,7 @@ jobs:
       id-token: write     # Required for OIDC token exchange with crates.io
       contents: write     # Required to be able to create a GitHub release
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - uses: rust-lang/crates-io-auth-action@v1
       id: auth