Misc deps/plugins updates (#216)
Misc deps/plugins updates (#216)

* Upgrade slf4j 1.7.2 -> 1.7.25

https://www.slf4j.org/news.html

* Upgrade JUnit 4.11 -> 4.12

https://github.com/junit-team/junit4/blob/master/doc/ReleaseNotes4.12.md

* Upgrade cloudbees-oss-parent 6 -> 8

matthewtckr/zendesk-java-client,cloudbees/zendesk-java-client