fix(deps): update dependency org.camunda.bpm:camunda-bom to v7.21.0 (main)

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.camunda.bpm:camunda-bom (source)	7.20.0 -> 7.21.0

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Release Notes

camunda/camunda-bpm-platform (org.camunda.bpm:camunda-bom)

### [`v7.21.0`](https://togithub.com/camunda/camunda-bpm-platform/compare/7.20.0...7.21.0) [Compare Source](https://togithub.com/camunda/camunda-bpm-platform/compare/7.20.0...7.21.0)

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