chore: 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/ci.yml

@@ -15,7 +15,7 @@ jobs:
         elixir: [1.17.x]
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: erlef/setup-beam@v1
       with:
         otp-version: ${{matrix.otp}}
@@ -55,7 +55,7 @@ jobs:
   #       options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
 
   #   steps:
-  #   - uses: actions/checkout@v5
+  #   - uses: actions/checkout@v6
   #   - uses: erlef/setup-beam@v1
   #     with:
   #       otp-version: 24.x
@@ -90,7 +90,7 @@ jobs:
     name: Formatter (1.17.x.x/27.x)
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: erlef/setup-beam@v1
       with:
         otp-version: 27.x

.github/workflows/release.yaml

@@ -20,7 +20,7 @@ jobs:
       - uses: googleapis/release-please-action@v4
         id: release
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ steps.release.outputs.release_created }}
 
       - uses: erlef/setup-beam@v1