RFR: CODETOOLS-7903226: Update version to 7.1

[Jonathan Gibbons]

jtreg 7 has been promoted and tagged.

The next version will be 7.1

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Commit messages:
 - CODETOOLS-7903226: Update version to 7.1

Changes: https://git.openjdk.org/jtreg/pull/94/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=94&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903226
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/94.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/94/head:pull/94

PR: https://git.openjdk.org/jtreg/pull/94