In a Maven project, how can I automatically update the version all child modules, plus the parent?

I have a multi-module project.

parent POM (1.0-SNAPSHOT)
|-- module1 (1.0-SNAPSHOT)
|-- module2 (1.0-SNAPSHOT)
`-- module3 (1.0-SNAPSHOT)

When I execute mvn release:prepare it verify that parent POM has a SNAPSHOT version and all dependent modules don’t have a SNAPSHOT version. How automatically update all child modules from SNAPSHOT to the next release version?

I would like automatically increment version for all modules.

In a Maven project, how can I automatically update the version all child modules, plus the parent?