SONARJAVA-6254 Use mise to install mvn in PrepareNextIteration.yml

[tomasz-tylenda-sonarsource]

Recent migration from GH runners to sonar runners broke the workflow, because our runners do not have mvn.

[sonar-review-alpha]

Summary

This PR adds the mise-action GitHub Actions step to the PrepareNextIteration workflow to install Maven. The sonar runners used by the workflow don't have mvn pre-installed (unlike the previous GitHub-hosted runners), so this step ensures Maven is available before the version normalization step runs.

What reviewers should know

What changed:
The only modification is in .github/workflows/PrepareNextIteration.yml — a single mise-action step was added immediately after checkout, specifying mise v2025.7.12.

What to verify:

• Confirm that mise version 2025.7.12 is the correct/stable version for your use case
• The step runs before any Maven-dependent steps, so the ordering is correct
• If you're unfamiliar with mise, note that it's a polyglot version manager (like nvm, pyenv, etc.) — reviewers should check that your team is comfortable with this as a dependency

No breaking changes — this is a pure addition that fixes a missing dependency issue on the new runners.

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[sonar-review-alpha]

LGTM! ✅

Clean, minimal fix. The mise.toml at the repo root declares maven = "3.9", so mise will install it when the action runs — the Update Version Number step's mvn call will work correctly. The pinned commit hash and mise version match what's used across all jobs in build.yml, keeping things consistent.

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[dorian-burihabwa-sonarsource]

Thanks for the fix. Could we update to a greater version of mise-action?

[sonarqube-next]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0 Dependency risks
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube