Fix LANG-related CPANTS failures

RT 95917: Fix LANG-related CPANTs failures in t/pipeline.t with the
following changes:

    * Limit the tr(1) substitution subcommand test to a discrete set of
      characters, rather than a character range which may not produce the
      same expected results on all locales and platforms

Other changes:

    * Update copyright year

    * Update authorship

    * Update distribution metadata with new authoritative GitHub URLs

    * Use more features of Test::More, like is()

    * Replace README with README.md