Document deprecation of `org.operaton.bpm:operaton-bpm-junit5`

[kthoms]

The classes from the module have been moved to the engine module. Clients should use org.operaton.bpm:operaton-engine:junit5 instead.

Document in release notes for version 1.1:

Add a note that module org.operaton.bpm:operaton-bpm-junit5 is deprecated. Users should use instead directly:

<dependency>
  <groupId>org.operaton.bpm</groupId>
  <artifactId>operaton-engine</artifactId>
  <classifier>junit5</classifier>
  <scope>test</scope>
</dependency>

related to operaton/operaton#2456