Remove dependency on jcenter

[William Morland]

A follow up from #1090

[Siham Hussein]

Is this similar to the issue in #1022 ?

[Ernest Sadykov]

@seehamrun I am not sure it is. Looks like #1022 is about shadow plugin, unlike jcenter dependency that we have to keep because of the docker plugin.

Now we are on Gradle 6 I think it makes sense to move to the latest versions of all the plugins. Hopefully it will fix everything.