p5-DateTime-TimeZone: update to 2.15.

2.15    2017-11-04

- Make the local zone lookup code handle the case where /usr/share/zoneinfo is
  a symlink, as it apparently is on recent versions of macOS (10.13). Fixed by
  Tom Wyant. GH #22 and #23.

2.14    2017-10-28

- This release is based on version 2017c of the Olson database. This release
  includes contemporary changes for Fiji, Namibia, Northern Cyprus, Sudan,
  Tonga, and Turks & Caicos.

(wiz)