Fix Security Vulnerabilities

Fix Security Vulnerabilities

- update logback (1.2.3 -> 1.2.13)
- update gson (2.8.4 -> 2.8.9)
- remove declaration of org.json (it's still a transitive
  dependency of the sdc-distribution-client), but in a newer version
- exclude mockito-core and powermock compile time deps that are pulled
  in by eelf-core
- resolve build warning about undeclared plugin version
  for the versions-maven-plugin

Issue-ID: MULTICLOUD-1507
Change-Id: Ica649d5225804afbc483f12e890f7cb08569d898
Signed-off-by: Fiete Ostkamp <Fiete.Ostkamp@telekom.de>