Bumped version to 1.4.3

[rhelmer]

Checklist for reviewer:

• [ ] The description should reference a bug or github issue, if relevant.
• [ ] There must be a CHANGELOG.md entry for any non-test change.
• [ ] Any change to the NPM commands must be carefully reviewed to make sure it won't break the Add-ons pipeline.
• [ ] Any version increase must follow the release process.