message: Update PULL_REQUEST_TEMPLATE.md
  Rolling back the last line on contribution licensing.
diff: ## Checklist
  - [ ] I have updated the CHANGELOG
  -By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
  +By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.
  