Update CHANGELOG.md in preparation for 0.43.0 release
Update CHANGELOG.md in preparation for 0.43.0 release

ponylang/ponyc,jemc/ponyc,dipinhora/ponyc,sgebbie/ponyc,ponylang/ponyc,dipinhora/ponyc,sgebbie/ponyc,jemc/ponyc,sgebbie/ponyc,jemc/ponyc,dipinhora/ponyc,sgebbie/ponyc,ponylang/ponyc,sgebbie/ponyc