exclude poko annotations as a runtime dependency

[evant]

This is only needed for compilation

note: excluding this way shows up in the pom file as:

    <dependency>
      <groupId>dev.drewhamilton.poko</groupId>
      <artifactId>poko-annotations-jvm</artifactId>
      <version>0.15.2</version>
      <scope>runtime</scope>
      <exclusions>
        <exclusion>
          <groupId>dev.drewhamilton.poko</groupId>
          <artifactId>*</artifactId>
        </exclusion>
     ....

instead of removing it completely which is a bit strange but it does seem to work fine on the consumer-side.