RFR: Update to JDK 13.0.1

[Erik Helin]

Hi all,

please review this small patch that updates to JDK 13.0.1 �� 

Thanks,
Erik

## Testing
- [x] `sh gradlew images` passes
- [x] `sh gradlew test` passes on Linux x64

----------------

Commits:
 - d6decf00: Update to JDK 13.0.1

Changes: https://git.openjdk.java.net/skara/pull/249/files
 Webrev: https://webrevs.openjdk.java.net/skara/249/webrev.00
  Stats: 14 lines in 3 files changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/skara/pull/249.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/249/head:pull/249

PR: https://git.openjdk.java.net/skara/pull/249