Prepare release 6.0.0

[mparticle-automation]

Preparing for release 6.0.0 from main.

• Bumped version to 6.0.0

[cursor]

PR Summary

Low Risk
Version and changelog-only changes with no code modifications in the PR diff.

Overview
Prepares the stable 6.0.0 release by promoting the version identifier from 6.0.0-rc.1 to 6.0.0 in VERSION.

The changelog gains a [6.0.0] - 2026-07-21 section under Core / Fixed, documenting that user attributes are waited on before Rokt selectPlacements runs (#727). No application or library source changes appear in this diff.

^{Reviewed by Cursor Bugbot for commit b268817. Bugbot is set up for automated code reviews on this repo. Configure here.}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud