Publish v4.0.0 of javy crate and v3.0.0 of javy-plugin-api

[jeffcharles]

Description of the change

Removes the -alpha1 suffixes from the javy library crate and javy-plugin-api crate and updates the CHANGELOGs for both to include a release date.

Why am I making this change?

I want to publish new versions of both crates that do not include Javy.JSON support.

Checklist

• I've updated the relevant CHANGELOG files if necessary. Changes to javy-cli and javy-plugin do not require updating CHANGELOG files.
• I've updated the relevant crate versions if necessary. Versioning policy for library crates
• I've updated documentation including crate documentation if necessary.