Add ruby.rpmlintrc.
    
    Ignore the false positive errors and warnings by the
    `rpmlint --file ruby.rpmlintrc`, that is executed by Zuul CI.
    
    You can run the command on your local like this.
    
    ```
    $ rpmlint --file ruby.rpmlintrc ruby.spec /var/lib/mock/fedora-rawhide-x86_64/result/*.rpm
    ```
    
    The `rpmlint` without `--file` option shows the original result.