RFR: CODETOOLS-7903453: Fix regex for tags in jtreg jcheck.conf

[Jonathan Gibbons]

Please review a fix for the regex for valid tag names

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Commit messages:
 - CODETOOLS-7903453: Fix regex for tags in jtreg jcheck.conf

Changes: https://git.openjdk.org/jtreg/pull/149/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=149&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903453
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/149.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/149/head:pull/149

PR: https://git.openjdk.org/jtreg/pull/149