RFR: 7903386: Update changelog for jtreg 7.1

[Christian Stein]

This PR updates the changelog file for `jtreg` 7.1+1

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Commit messages:
 - Update changelog for `jtreg` 7.1+1

Changes: https://git.openjdk.org/jtreg/pull/137/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=137&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903386
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/137.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/137/head:pull/137

PR: https://git.openjdk.org/jtreg/pull/137