Add codecov as part of ci checks

Osie uses codecov already, this PR extends its use with the tink
repository.

Right now there is not support for PR comments or things like that. It
just updates codecov

Signed-off-by: Gianluca Arbezzano <gianarb92@gmail.com>

.github/workflows/ci.yaml

@@ -23,8 +23,10 @@ jobs:
       uses: golangci/golangci-lint-action@v1
       with:
         version: v1.30
-    - name: go vet
-      run: go test ./...
+    - name: go test
+      run: go test -coverprofile=coverage.txt ./...
+    - name: upload codecov
+      run: bash <(curl -s https://codecov.io/bash)
     - name: Build binaries
       run: make
     - name: Upload tink-server binary

README.md

@@ -1,6 +1,7 @@
 # Tinkerbell
 
 [![Build Status](https://cloud.drone.io/api/badges/tinkerbell/tink/status.svg)](https://cloud.drone.io/tinkerbell/tink)
+[![codecov](https://codecov.io/gh/tinkerbell/tink/branch/master/graph/badge.svg)](https://codecov.io/gh/tinkerbell/tink)
 
 It is comprised of following five major components: