Release/v0.15.0

[github-actions]

This pull request was created because a release pipeline completed successfully. If this is a patch release (the release version does not end in 0, e.g. "v1.2.5") that was triggered as part of its weekly schedule, you may close this PR directly, unless you want it to be logged on the website. A git tag was created regardless, so people can check it out.

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Note:

• for minor and major releases, the release article should be created, meant as a kickstarter for the final release. The template is generated, please ask contributors to fill it out
• release information file is used for updating the release history page

[pascalwhoop]

• The "Experiments" section has a contradiction - it states "No experiment reports in this release" but then lists multiple items below it. Those items appear to be bug fixes and technical enhancements rather than experiments.
• Consider removing items like the OpenAI key reference update and PR 1962 if they're considered unnecessary bloat.
• The Redis run book section also seems verbose.
• Moving the summary to the top of the document would be more helpful than placing it at the bottom.