plugin should add a space character when displaying failed report files

[xzel23]

When more than one report file is generated, i.e. when both HTML and XML outputs are active, SpotBugs outputs a message with both file paths concatenated by a single comma. This makes it harder to read and confuses link detection in IDEs like IntelliJ IDEA so that it is not possible to open the report file by clicking on the link.

Current output:

    > Verification failed: SpotBugs ended with exit code 1. See the 
report at: file:///Users/axelhowind/IdeaProjects/utility/utility/build/reports/spotbugs.html,file:///Users/axelhowind/IdeaProjects/utility/utility/build/reports/spotbugs.xml

Should be:

    > Verification failed: SpotBugs ended with exit code 1. See the 
report at: file:///Users/axelhowind/IdeaProjects/utility/utility/build/reports/spotbugs.html, file:///Users/axelhowind/IdeaProjects/utility/utility/build/reports/spotbugs.xml

[github-actions]

🎉 This issue has been resolved in version 5.2.4 🎉

The release is available on:

• 5.2.4
• GitHub release

Your semantic-release bot 📦🚀

[github-actions]

🎉 This issue has been resolved in version 6.0.0-rc.3 🎉

The release is available on:

• 6.0.0-rc.3
• GitHub release

Your semantic-release bot 📦🚀