Prepare release 3.2.3

[jsoriano]

Prepare changelog for 3.2.3 release. It includes some new required fields, what is a breaking change but only when defining agentless deployment modes, what is in tech preview. It also includes additional checks for the changelog.

[jsoriano]

test integrations

[elastic-vault-github-plugin-prod[bot]]

Created or updated PR in integrations repository to test this version. Check https://github.com/elastic/integrations/pull/11395

[elasticmachine]

:green_heart: Build Succeeded

• Buildkite Build
• Commit: 10daee1462883800cb106e3a93be28f4defae526

cc @jsoriano