enable Reproducible Builds

[hboutemy]

Motivation:

see https://maven.apache.org/guides/mini/guide-reproducible-builds.html

Conformance:

You should have signed the Eclipse Contributor Agreement as explained in https://github.com/eclipse/vert.x/blob/master/CONTRIBUTING.md Please also make sure you adhere to the code style guidelines: https://github.com/vert-x3/wiki/wiki/Vert.x-code-style-guidelines

[vietj]

shouldn't this be in vertx parent pom instead ?

[hboutemy]

plugins versions can go to parent, yes timestamp in the project is useful to get its value updated during release