[jfx21u] RFR: 8323830: Change JavaFX release version to 21.0.3 in jfx21u

[Johan Vos]

Start work on 21.0.3

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Commit messages:
 - Increase JavaFX version to 21.0.3 before any other commits go in.

Changes: https://git.openjdk.org/jfx21u/pull/41/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx21u&pr=41&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323830
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx21u/pull/41.diff
  Fetch: git fetch https://git.openjdk.org/jfx21u.git pull/41/head:pull/41

PR: https://git.openjdk.org/jfx21u/pull/41