Dataproc - June 24th, 2020 [Change, Fix]

## Change New [subminor image versions](https://cloud.google.com/dataproc/docs/concepts/versioning/dataproc-versions#supported%5Fcloud%5Fdataproc%5Fversions): 1.2.100-debian9, 1.3.60-debian9, 1.4.31-debian9, 1.3.60-debian10, 1.4.31-debian10, 1.5.6-debian10, 1.3.60-ubuntu18, 1.4.31-ubuntu18, 1.5.6-ubuntu18, preview 2.0.0-RC2-debian10, and preview 2.0.0-RC2-ubuntu18. ## Change * **Image 2.0 preview**: * [SPARK-22404](https://issues.apache.org/jira/browse/SPARK-22404): set`spark.yarn.unmanagedAM.enabled` property to `true` on clusters where Kerberos is not enabled to run Spark Application Master in driver (not managed in YARN) to improve job execution time. * Updated R version to 3.6 * Updated Spark to [3.0.0 version](https://spark.apache.org/releases/spark-release-3-0-0.html) * **Image 1.5** * Updated R version to 3.6 ## Fix Fixed a quota validation bug where accelerator counts were squared before validation -- for example, previously if you requested 8 GPUs, Dataproc validated whether your project had quota for `8^2=64` GPUs.