Another fix for the copyright pre-commit-hook

[KineticTheory]

Background

• For new files, the script was setting a date range like 2021-2021. Catch this special case and just insert a single date.
• Also, pre-commit-copyright wasn't aborting the commit process when die was called. Replace die with echo && exit 1.

Status

• Reference:
  • Pre-Merge Code Review
  • CDash Status
• Checks
  • [x] Travis/Appveyor CI checks pass
  • [x] Code coverage does not decrease
  • [ ] Valgrind test passes
  • [ ] Toss3 checks pass
  • [ ] Trinitite checks pass
  • [ ] Code reviewed/approved, sufficient DbC checks, testing, documentation

[codecov[bot]]

Codecov Report

Merging #1118 (6e3d2ed) into develop (d81b6e6) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           develop   #1118   +/-   ##
=======================================
  Coverage     88.9%   88.9%           
=======================================
  Files          373     373           
  Lines        19568   19568           
=======================================
  Hits         17415   17415           
  Misses        2153    2153           

[RyanWollaeger]

LGTM - can merge if there are no objections