ci: bump actions/checkout from 6.0.3 to 7.0.1

Bumps [actions/checkout](https://github.com/actions/checkout) from 6.0.3 to 7.0.1.
- [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/df4cb1c069e1874edd31b4311f1884172cec0e10...3d3c42e5aac5ba805825da76410c181273ba90b1)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 7.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/release_plugin.yml

@@ -22,7 +22,7 @@ jobs:
     steps:
       # 1. Stáhne kód z tagu, který běh spustil
       - name: Checkout code
-        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       # 2. Vytvoří ZIP (předpokládá, že kód je ve složce 'amcr_viewer')
       - name: Zip Plugin