add codecov to action, fix README build status

.github/workflows/main.yml

@@ -16,7 +16,6 @@ jobs:
         uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go-version }}
-      # You can test your matrix by printing the current Go version
       - name: Display Go version
         run: go version
       - name: Install dependencies
@@ -35,5 +34,8 @@ jobs:
           go build examples/stressor/client/main.go
           go build examples/authentication/auth.go
           go build examples/microchat/microchat.go
-
-      # TODO: upload code coverage results
+      - uses: codecov/codecov-action@v3
+        with:
+          files: ./coverage.txt
+          fail_ci_if_error: true
+          verbose: true

README.md

@@ -1,6 +1,4 @@
-
-# golongpoll [![build workflow](https://github.com/jcuga/golongpoll/actions/workflows/main.yml/badge.svg)
-](https://travis-ci.com/jcuga/golongpoll) [![codecov](https://codecov.io/gh/jcuga/golongpoll/branch/master/graph/badge.svg)](https://codecov.io/gh/jcuga/golongpoll)  [![GoDoc](https://godoc.org/github.com/jcuga/golongpoll?status.svg)](https://godoc.org/github.com/jcuga/golongpoll) [![Go Report Card](https://goreportcard.com/badge/jcuga/golongpoll)](https://goreportcard.com/report/jcuga/golongpoll)
+# golongpoll [![build workflow](https://github.com/jcuga/golongpoll/actions/workflows/main.yml/badge.svg)] [![codecov](https://codecov.io/gh/jcuga/golongpoll/branch/master/graph/badge.svg)](https://codecov.io/gh/jcuga/golongpoll)  [![GoDoc](https://godoc.org/github.com/jcuga/golongpoll?status.svg)](https://godoc.org/github.com/jcuga/golongpoll) [![Go Report Card](https://goreportcard.com/badge/jcuga/golongpoll)](https://goreportcard.com/report/jcuga/golongpoll)
 Golang long polling library. Makes web pub-sub easy via HTTP long-poll servers and clients.  Supports golang v1.9 and up.
 
 ## Resources