Bump actions/checkout from 2 to 6 (#159)

* Bump actions/checkout from 2 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...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>

* Update CITATION.cff commit and date-released [skip ci]

---------

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

Author: dependabot[bot]

.github/workflows/docker-build-and-push.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v6
 
       - name: Login to Docker Hub
         uses: docker/login-action@v1

CITATION.cff

@@ -37,12 +37,12 @@ identifiers:
     value: 10.5281/zenodo.17977921
     description: Edirom Online Frontend
 repository-code: https://github.com/Edirom/Edirom-Online-Frontend
-commit: c6f36354790dc60d727e5f1810fc00af55465b1a
+commit: eae7a8d0a87cd6958d959a7e06cb4c2eb2e0870c
 abstract: >-
   Edirom Online Frontend is the frontend for the Edirom 
   Online which is used for the presentation and
   analysis of critical musical editions in a digital format,
   particularly in the fields of musicology and philology.
 license: GPL-3.0
 version: v1.2.0
-date-released: 2026-02-19
+date-released: 2026-02-23