CI: Use coverall (#80)

Author: earthboundkid

.github/workflows/go.yml

@@ -15,4 +15,7 @@ jobs:
     - name: Get dependencies
       run: go mod download
     - name: Test
-      run: go test -race -v ./...
+      run: go test -race -v -coverprofile=profile.cov ./...
+    - uses: shogo82148/actions-goveralls@v1
+      with:
+        path-to-profile: profile.cov

README.md

@@ -1,4 +1,4 @@
-# Requests [![GoDoc](https://godoc.org/github.com/carlmjohnson/requests?status.svg)](https://godoc.org/github.com/carlmjohnson/requests) [![Go Report Card](https://goreportcard.com/badge/github.com/carlmjohnson/requests)](https://goreportcard.com/report/github.com/carlmjohnson/requests) [![Mentioned in Awesome Go](https://awesome.re/mentioned-badge.svg)](https://github.com/avelino/awesome-go)
+# Requests [![GoDoc](https://godoc.org/github.com/carlmjohnson/requests?status.svg)](https://godoc.org/github.com/carlmjohnson/requests) [![Go Report Card](https://goreportcard.com/badge/github.com/carlmjohnson/requests)](https://goreportcard.com/report/github.com/carlmjohnson/requests) [![Coverage Status](https://coveralls.io/repos/github/carlmjohnson/requests/badge.svg)](https://coveralls.io/github/carlmjohnson/requests) [![Mentioned in Awesome Go](https://awesome.re/mentioned-badge.svg)](https://github.com/avelino/awesome-go)
 
 ![Requests logo](/img/gopher-web.png)