If you only need to bump the WP 'Tested up to' version, and you don't need a full deployment:

1. Create a branch off develop, with a branch name starting with bump-tested-up-to. It could be bump-tested-up-to/6.5.
2. Bump the 'Tested up to' version.
3. Open a PR with that commit.
4. In CI/CD there will be a job approval-for-deploy-tested-up-to-bump.
5. Approve that job.
6. CI/CD will deploy to wp.org svn, only updating that 'Tested up to' version. It won't edit any other file.