RFR: 7903388: Update version to 7.2

[Christian Stein]

The next promoted version will be 7.2

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Commit messages:
 - 7903388: Update version to 7.2

Changes: https://git.openjdk.org/jtreg/pull/138/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=138&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903388
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/138.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/138/head:pull/138

PR: https://git.openjdk.org/jtreg/pull/138