[jdk21u-dev] RFR: 8331266: Bump update version for OpenJDK: jdk-21.0.5

[Goetz Lindenmaier]

We need this to start the next release.

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Commit messages:
 - 8331266: Bump update version for OpenJDK: jdk-21.0.5

Changes: https://git.openjdk.org/jdk21u-dev/pull/947/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331266
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/947.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/947/head:pull/947

PR: https://git.openjdk.org/jdk21u-dev/pull/947