build(deps): bump actions/checkout from 5 to 6

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>

Author: dependabot[bot]

.github/workflows/containers.yml

@@ -24,7 +24,7 @@ jobs:
     timeout-minutes: 30
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Build Docker container
         run: docker build -t local docker/${{ matrix.shmem }}/
       - name: run shmem4py test-1

.github/workflows/native.yml

@@ -36,7 +36,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Setup MPI (${{ matrix.mpi }})
       uses: mpi4py/setup-mpi@v1

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
 
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Set SOURCE_DATE_EPOCH
       run:  |
@@ -84,7 +84,7 @@ jobs:
     steps:
 
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Download distribution artifact
       uses: actions/download-artifact@v6