Update Jenkins version to 2.387.3 in pom.xml

[krisstern]

Description

Updated the Jenkins version to 2.387.3 in pom.xml as suggested by https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/#changing-the-minimum-required-version.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira - N/A
• Link to relevant pull requests, esp. upstream and downstream changes - N/A
• Ensure you have provided tests - that demonstrates feature works or fixes the issue - N/A