[jdk13u-dev] RFR: 8253632: Bump update version for OpenJDK: jdk-13.0.6

[Yuri Nesterenko]

As usual, to continue development of jdk13u, we need to _bump_ some default numbers before opening the team repository
for the next release.

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Commit messages:
 - 8253632: Bump update version for OpenJDK: jdk-13.0.6

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/2/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=2&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253632
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/2.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/2/head:pull/2

PR: https://git.openjdk.java.net/jdk13u-dev/pull/2