Bump actions/checkout from 5 to 6 (#150)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/cache-cleanup.yml

@@ -9,7 +9,7 @@ jobs:
   cleanup:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Cleanup
         run: |
           gh extension install actions/gh-actions-cache

.github/workflows/publish.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Install Rust toolchain

.github/workflows/rust.yml

@@ -43,7 +43,7 @@ jobs:
           - { target: x86_64-unknown-linux-gnu }     
           - { target: armv7-unknown-linux-gnueabihf }
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install toolchain
         run: |
           rustup toolchain install stable --no-self-update --profile minimal --target ${{ matrix.target }}
@@ -62,7 +62,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: "recursive"
       - name: Install toolchain
@@ -80,7 +80,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: "recursive"