[jfx17u] RFR: 8348318: Change JavaFX release version to 17.0.15 in jfx17u

[Johan Vos]

Bump version to 17.0.15

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Commit messages:
 - Bump version to 17.0.15

Changes: https://git.openjdk.org/jfx17u/pull/224/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=224&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348318
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx17u/pull/224.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u.git pull/224/head:pull/224

PR: https://git.openjdk.org/jfx17u/pull/224