pvws: R3 -> R4

[minijackson]

Fixes #615

Changelog: https://github.com/ornl-epics/pvws/releases/tag/R4

cc @achoqt for review.

Checklist

• Testing:

  • The feature has automated tests
  • Tests were run
  • If not, explain how you tested your changes

• Documentation:

  • The feature is documented
  • The documentation is up to date
  • Release notes:
    • Added an entry if the change is breaking or significant
    • Added an entry when adding a new feature