Improve MAVEN build Performance

[ChenZhangg]

Parallel builds in Maven 3 Maven 3.x has the capability to perform parallel builds.

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If there are any inappropriate modifications in this PR, please give me a reply and I will change them.

[liry]

Hi, @ChenZhangg, thanks for contribution, but we first need to migrate out of Travis CI: "Since June 15th, 2021, the building on travis-ci.org is ceased."

[liry]

BTW, I've tried the parallel build on localhost and got this warning:

[WARNING] *****************************************************************
[WARNING] * Your build is requesting parallel execution, but project      *
[WARNING] * contains the following plugin(s) that have goals not marked   *
[WARNING] * as @threadSafe to support parallel building.                  *
[WARNING] * While this /may/ work fine, please look for plugin updates    *
[WARNING] * and/or request plugins be made thread-safe.                   *
[WARNING] * If reporting an issue, report it against the plugin in        *
[WARNING] * question, not against maven-core                              *
[WARNING] *****************************************************************
[WARNING] The following plugins are not marked @threadSafe in jadler-core:
[WARNING] org.apache.maven.plugins:maven-enforcer-plugin:1.0
[WARNING] org.pitest:pitest-maven:1.1.11
[WARNING] Enable debug to see more precisely which goals are not marked @threadSafe.
[WARNING] *****************************************************************

maybe we just need to raise those plugin versions

[liry]

FYI: builds migrated to GH Actions in #157

[ChenZhangg]

pitest The newest version is 1.7.0
maven-enforcer-plugin The newest version is 3.0.0
Maybe I can upgrade them?

[liry]

Sure you can, but when I tried to simply upgrade it, pitest failed with "Mutation score of 69 is below threshold of 70". So it's not gonna be that easy.