Deps: Bump actions/checkout

Bumps the dependencies group in /mattermost-notify with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 6.0.1 to 6.0.2
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@8e8c483...de0fac2)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
...

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

Author: dependabot[bot]

mattermost-notify/action.yml

@@ -83,7 +83,7 @@ runs:
       # we need a checkout to determine the commit-message per git
       # if commit is set but commit-message is not
       if: inputs.commit && !inputs.commit-message
-      uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       with:
         ref: ${{ inputs.commit }}