chore(deps): bump jenkins-x-plugins/jx-release-version

Bumps [jenkins-x-plugins/jx-release-version](https://github.com/jenkins-x-plugins/jx-release-version) from 2.7.6 to 2.7.8.
- [Release notes](https://github.com/jenkins-x-plugins/jx-release-version/releases)
- [Changelog](https://github.com/jenkins-x-plugins/jx-release-version/blob/v2.7.8/changelog.md)
- [Commits](jenkins-x-plugins/jx-release-version@v2.7.6...v2.7.8)

---
updated-dependencies:
- dependency-name: jenkins-x-plugins/jx-release-version
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/jenkins-x-release.yaml

@@ -27,7 +27,7 @@ jobs:
         files: ./build/reports/cover.txt
     - id: prep
       name: next release version
-      uses: jenkins-x-plugins/[email protected].6
+      uses: jenkins-x-plugins/[email protected].8
     - env:
         GITHUB_TOKEN: ${{ secrets.GIT_BOT_TOKEN }}
         REPO_NAME: ${{ github.event.repository.name }}