Plugin Release v3.4.0-maven

## Requirements
- [x] ⚠️ Ensure the release process has succeeded before proceeding

## GCS
- [x] Run `./jib-maven-plugin/scripts/update_gcs_latest.sh 3.4.0` script to update GCS with the latest version number

## Github
- [x] Update [CHANGELOG.md](https://github.com/GoogleContainerTools/jib/blob/master/jib-maven-plugin/CHANGELOG.md)
- [x] Update [README.md](https://github.com/GoogleContainerTools/jib/blob/master/jib-maven-plugin/README.md)
- [x] Search/replace the old published version with the new published version in [examples](https://github.com/GoogleContainerTools/jib/tree/master/examples)
- [x] Publish [Release](https://github.com/GoogleContainerTools/jib/releases/tag/untagged-39c54898cb7085f46a51)
- [x] Merge PR (https://github.com/GoogleContainerTools/jib/pull/4105)

#### Jib-Extensions
- [x] Update versions in [Jib Extensions](https://github.com/GoogleContainerTools/jib-extensions)
- [x] If there were Gradle API or Jib API changes, double-check compatibility and update Version Matrix on jib-extensions. It may require re-releasing first-party extensions. See [jib-extensions#45](https://github.com/GoogleContainerTools/jib-extensions/pull/45), [jib-extensions#44](https://github.com/GoogleContainerTools/jib-extensions/pull/44), and [jib-extensions#42](https://github.com/GoogleContainerTools/jib-extensions/pull/42)

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