4.3.0 release

[adamralph]

• beta 1 - 24th November
  • MinVer
  • minver-cli
  • https://github.com/adamralph/bullseye
  • https://github.com/adamralph/simple-exec
  • @iampluque - #839 (comment)
  • @lonix1 - #839 (comment)
• ensure README.md reflects new version
• update changelog
• create next milestone
• build tag
• push package
• close milestone
• tweet, mentioning contributors - tweet-1618953099007389697