Update dependencies (security updates)

[HeinrichAD]

Short: update maven artifacts and docker base image (as well as reduce there image size). This PR also close #253 that mentioned that the current used jetty version is vulnerable.

Update maven artifacts

• checkstyle stopped supporting jdk8 with version 10.0.0
  https://checkstyle.org/releasenotes.html#Release_10.0
• PDF dependency was missing in the jdk8 pom file
  • Maybe it would be better to creating a parent pom? In that case all PlantUML dependencies could be in the parent pom and one would only have to maintain the parent pom file.
  • Why doesn't exist any PDF test?
• add rule to ignore version update hint with -dev followed by a dot and date (e.g. 0.37.0-dev.20230308)
• migration from JUnit4 to JUnit5

Docker

There were same base image and naming changes for the jetty and tomcat images plantuml-server uses. Therefore, plantuml-server uses a rather old and vulnerable image, since there are no updates according to the old naming scheme.

• update base images for jetty and tomcat
• add a alpine version for jetty
  Note:
  • tomcat has no official alpine version => no plantuml alpine tomcat image
  • jetty alpine version is only available for people who build it by there own
• add autoremove and clean commands after graphviz installation. This reduces the images by about ~280 MB.
  • Jetty: 704 MB -> 413 MB (reduced by ~40%)
  • Tomcat: 905 MB -> 632 MB (reduced by ~30%)

[HeinrichAD]

As a hint why the update could be quite important. (I used trivy for the analysis.):

Jetty

Current available docker image online

plantuml/plantuml-server:jetty (debian 11.2)
============================================
Total: 516 (UNKNOWN: 6, LOW: 314, MEDIUM: 90, HIGH: 90, CRITICAL: 16)

After the update

plantuml-server:jetty-local (ubuntu 22.04)
==========================================
Total: 23 (UNKNOWN: 0, LOW: 20, MEDIUM: 3, HIGH: 0, CRITICAL: 0)

Tomcat

Current available docker image online

plantuml/plantuml-server:tomcat (debian 11.4)
=============================================
Total: 499 (UNKNOWN: 6, LOW: 313, MEDIUM: 84, HIGH: 87, CRITICAL: 9)

After the update

plantuml-server:tomcat-local (ubuntu 22.04)
===========================================
Total: 23 (UNKNOWN: 0, LOW: 20, MEDIUM: 3, HIGH: 0, CRITICAL: 0)