Make plugindriver version consistent

[huehnerlady]

In our project we have the following config:

configurations {
    all {
      resolutionStrategy {
        failOnVersionConflict()
        force(dependencyVersions)
      }
    }
  }

With that we see that with the update to pact 4.6.14 there is a new version conflict of the plugin driver

Looking in the project I can see, that there is io.pact.plugin.driver:core:0.5.1 and io.pact.plugin.driver:core:0.4.2 defined, depending if you use api or implementation.

I aligned the version now. In our projects we have either reminder comments or we have variables.
I here thought the least intrusive way is a comment to hopefully remind people to update the version in 2 places in future.

[rholshausen]

Oops! Thank for the PR!