Bump actions/checkout from 6.0.2 to 6.0.3 (#350)

Bumps [actions/checkout](https://github.com/actions/checkout) from 6.0.2 to 6.0.3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@de0fac2...df4cb1c)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/auto-update.yml

@@ -8,7 +8,7 @@ jobs:
   update-jpostcode-data:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
     - name: Set up Ruby
       uses: ruby/setup-ruby@89f90524b88a01fe6e0b732220432cc6142926af # v1.313.0
       with: