io.micronaut:micronaut-runtime should be removed

[sdelamo]

Users should not need to depend on Micronaut Runtime:

If the users have a dependency such as:

<dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-runtime</artifactId>
      <scope>compile</scope>
    </dependency>

we should remove it.