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] <[email protected]>

Author: dependabot[bot]

.github/workflows/apptainer_build.yml

@@ -16,7 +16,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/run_tests_cli.yml

@@ -34,7 +34,7 @@ jobs:
             with:
                 python-version: ${{ matrix.python-version }}
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0
@@ -60,7 +60,7 @@ jobs:
         if: github.repository_owner == 'cpp-lln-lab'
         steps:
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/run_tests_notebooks.yml

@@ -36,7 +36,7 @@ jobs:
                 release: R2023a
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/tests.yml

@@ -65,7 +65,7 @@ jobs:
                 pip install datalad
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0
@@ -160,7 +160,7 @@ jobs:
                 pip install datalad
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0
@@ -264,7 +264,7 @@ jobs:
                 pip install datalad
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/tests_octave.yml

@@ -74,7 +74,7 @@ jobs:
                 python-version: '3.11'
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/tests_windows.yml

@@ -72,7 +72,7 @@ jobs:
                 python-version: '3.11'
 
         -   name: Clone bidspm
-            uses: actions/checkout@v5
+            uses: actions/checkout@v6
             with:
                 submodules: recursive
                 fetch-depth: 0

.github/workflows/validation.yml

@@ -16,7 +16,7 @@ jobs:
     validate_cff:
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: Check whether the citation metadata from CITATION.cff is valid
             uses: citation-file-format/[email protected]
             with: