[jdk11u-dev] RFR: 8309108: Bump update version for OpenJDK: jdk-11.0.21

[Goetz Lindenmaier]

The requires version bump.

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

Commit messages:
 - 8309108: Bump update version for OpenJDK: jdk-11.0.21

Changes: https://git.openjdk.org/jdk11u-dev/pull/1914/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1914&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309108
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1914.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/1914/head:pull/1914

PR: https://git.openjdk.org/jdk11u-dev/pull/1914