Harald Radi

now the "api" configuration is not available anymore: https://docs.gradle.org/current/userguide/java_library_plugin.html#sec:java_library_separation

``` * What went wrong: A problem occurred evaluating project ':contract-client'. > Could not find method api() for arguments [io.cloudflight.conto:conto-signature-api] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler. ```

Also see https://github.com/cloudflightio/autoconfigure-gradle-plugin/issues/195

This is quite a breaking change.