RFR: 8124: Fix the release notes generator

[Marcus Hirt]

Not sure how this ever compiled and ran under JDK 17. Discovered when importing everything into Eclipse 2023-09.

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

Commit messages:
 - 8124: Fix the release notes generator

Changes: https://git.openjdk.org/jmc/pull/520/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=520&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8124
  Stats: 8 lines in 1 file changed: 1 ins; 5 del; 2 mod
  Patch: https://git.openjdk.org/jmc/pull/520.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/520/head:pull/520

PR: https://git.openjdk.org/jmc/pull/520