fix badges

README.md

@@ -1,6 +1,6 @@
 # either-result
 
-[![Hackage](https://matrix.hackage.haskell.org/api/v2/packages/either-result/badge)](http://hackage.haskell.org/package/either-result) [![GitHub Actions: test](https://github.com/kakkun61/either-result/workflows/test/badge.svg)](https://github.com/kakkun61/either-result/actions?query=workflow%3Atest) [![GitHub Actions: lint](https://github.com/kakkun61/either-result/workflows/lint/badge.svg)](https://github.com/kakkun61/either-result/actions?query=workflow%3Alint) [![Join the chat at https://gitter.im/either-result/community](https://badges.gitter.im/either-result/community.svg)](https://gitter.im/either-result/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Sponsor](https://img.shields.io/badge/Sponsor-%E2%9D%A4-red?logo=GitHub)](https://github.com/sponsors/kakkun61)
+[![Hackage](https://matrix.hackage.haskell.org/api/v2/packages/either-result/badge)](http://hackage.haskell.org/package/either-result) [![GitHub Actions: main](https://github.com/kakkun61/either-result/workflows/main/badge.svg)](https://github.com/kakkun61/either-result/actions?query=workflow%3Amain) [![Join the chat at https://gitter.im/either-result/community](https://badges.gitter.im/either-result/community.svg)](https://gitter.im/either-result/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Sponsor](https://img.shields.io/badge/Sponsor-%E2%9D%A4-red?logo=GitHub)](https://github.com/sponsors/kakkun61)
 
 `Result a` is a wrapper of `Either String a`, but `Result` is an instance of `MonadFail`.