Fixing configuration for publishing to maven.

[baldawar]

This stopped working after the latest maven-source-plugin version bump

Description of changes:

This change was necessary to make 1.4.0 published to maven.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[baldawar]

Before fixing this, was seeing following error

[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ event-ruler ---
[INFO] 
[INFO] >>> maven-source-plugin:3.3.0:jar (attach-sources) > generate-sources @ event-ruler >>>
[INFO] 
[INFO] --- maven-checkstyle-plugin:3.3.0:check (validate) @ event-ruler ---
[INFO] Starting audit...
Audit done.
[INFO] You have 0 Checkstyle violations.
[INFO] 
[INFO] <<< maven-source-plugin:3.3.0:jar (attach-sources) < generate-sources @ event-ruler <<<
[INFO] 
[INFO] 
[INFO] --- maven-source-plugin:3.3.0:jar (attach-sources) @ event-ruler ---
[INFO] 
[INFO] --- maven-source-plugin:3.3.0:jar-no-fork (attach-sources) @ event-ruler ---
[ERROR] We have duplicated artifacts attached.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  55.144 s
[INFO] Finished at: 2023-10-10T19:21:53-07:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-source-plugin:3.3.0:jar-no-fork (attach-sources) on project event-ruler: Presumably you have configured maven-source-plugn to execute twice times in your build. You have to configure a classifier for at least on of them. -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException