chore(deps): bump actions/checkout from 5 to 6 in /.github/workflows (#89)

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/build_directory_md.yml

@@ -16,7 +16,7 @@ jobs:
   build_directory_md:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: jiro4989/setup-nim-action@v2
         with:

.github/workflows/check_code_format.yml

@@ -14,7 +14,7 @@ jobs:
     name: check format code
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/nim_test.yml

@@ -23,7 +23,7 @@ jobs:
           - '2.2.6'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: jiro4989/setup-nim-action@v2
         with:

.github/workflows/nim_test_cyclic.yml

@@ -20,7 +20,7 @@ jobs:
           - 'devel'
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: jiro4989/setup-nim-action@v2
         with: