Release 14.3.1 into trunk

[iangmaia]

Releasing new version 14.3.1.

What's Next

PR Author: Be sure to create and publish a GitHub Release pointing to trunk once this PR gets merged,
copy/pasting the following text as the GitHub Release's description:

### Internal Changes

- Remove `activesupport` as a runtime dependency — replace the only production usage (`deep_dup`) with `Marshal` deep copy — and move it to a dev-only dependency for specs. [#709]
- Update RuboCop configuration: fix obsolete `Naming/PredicateName` cop rename, move permanent style choices from `.rubocop_todo.yml` to `.rubocop.yml`, and fix a `Style/FileOpen` violation. [#709]