Update CI badge for README (#516)

Match open-telemetry/opentelemetry-go#1440

README.md

@@ -1,6 +1,6 @@
 # OpenTelemetry-Go Contrib
 
-[![Circle CI](https://circleci.com/gh/open-telemetry/opentelemetry-go-contrib.svg?style=svg)](https://circleci.com/gh/open-telemetry/opentelemetry-go-contrib)
+[![build_and_test](https://github.com/open-telemetry/opentelemetry-go-contrib/workflows/build_and_test/badge.svg)](https://github.com/open-telemetry/opentelemetry-go-contrib/actions?query=workflow%3Abuild_and_test+branch%3Amaster)
 [![Docs](https://godoc.org/go.opentelemetry.io/contrib?status.svg)](https://pkg.go.dev/go.opentelemetry.io/contrib)
 [![Go Report Card](https://goreportcard.com/badge/go.opentelemetry.io/contrib)](https://goreportcard.com/report/go.opentelemetry.io/contrib)
 [![Gitter](https://badges.gitter.im/open-telemetry/opentelemetry-go.svg)](https://gitter.im/open-telemetry/opentelemetry-go?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)