fix(java): adjust children module version of pom to avoid warning

[Thespica]

Describe the enhancement requested

When running maven-projects, there are warning like:

[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.apache.graphar:graphar-info:jar:0.12.0-SNAPSHOT
[WARNING] 'version' contains an expression but should be a constant. @ org.apache.graphar:graphar-info:${graphar.version}, /home/john/graphar/incubator-graphar/maven-projects/info/pom.xml, line 37, column 14
[WARNING] 'version' contains an expression but should be a constant. @ org.apache.graphar:graphar-root:${graphar.version}, /home/john/graphar/incubator-graphar/maven-projects/pom.xml, line 32, column 14
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]

should remove version property, since child module will automatically inherit the version from the parent, and add comment to notice that.

refer: https://stackoverflow.com/questions/1981151/warning-on-using-project-parent-version-as-the-version-of-a-module-in-maven-3

Component(s)

Java, Spark