After the release is finished and the tests have passed:

• The "old version" number needs to be updated in multiple projects and locations (see guide)
• New upgrade scripts need to be created
• A new instance migration project needs to be added

The guide for these changes can be found here:
https://github.com/camunda/camunda-bpm-dev-docs/blob/master/releases/Performing-a-Minor-Release.md#camunda-bpm-platform-code-changes