chore(deps): bump actions/checkout from 5 to 6 (#288)

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/file-freshness-pr.yml

@@ -8,7 +8,7 @@ jobs:
   update-external-files:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: >
           curl -sL 'https://www.indicepa.gov.it/public-services/opendata-read-service.php?dstype=FS&filename=amministrazioni.txt'
           | tail -n +2

.github/workflows/lint.yml

@@ -4,7 +4,7 @@ jobs:
   go-lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-go@v6
         with:
           go-version: "1.25"

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
         uses: docker/setup-buildx-action@v3
 
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Unshallow
         run: git fetch --prune --unshallow
       - name: Docker Login

.github/workflows/tests.yml

@@ -4,7 +4,7 @@ jobs:
   tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-go@v6
         with:
           go-version: "1.24"