p5-DateTime-TimeZone: update to 2.42

pkgsrc-specific change: while here, express test dependencies as such.

2.42    2020-10-16

- This release is based on version 2020c of the Olson database. This release
  includes contemporary changes for Fiji.

2.41    2020-10-07

- The last release was missing all the generated data files. Oops! Reported by
  Paul Howarth. GH #43.

- Added a custom dzil plugin to make sure that the release has all of the
  generated data files.

2.40    2020-10-07

- This release is based on version 2020b of the Olson database. This release
  includes contemporary changes for Morocco, Casey Station, and the
  Yukon. This release also removes the very long-deprecated "US/Pacific-New"
  zone name.

(gutteridge)