Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...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>

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
     runs-on: blacksmith-4vcpu-ubuntu-2404
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Go
         uses: actions/setup-go@v6
@@ -60,7 +60,7 @@ jobs:
       packages: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Blacksmith Builder
         uses: useblacksmith/setup-docker-builder@v1
@@ -103,7 +103,7 @@ jobs:
       is_tag: ${{ steps.version.outputs.is_tag }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 
@@ -143,7 +143,7 @@ jobs:
             runner: blacksmith-4vcpu-ubuntu-2404-arm
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Blacksmith Builder
         uses: useblacksmith/setup-docker-builder@v1