Fix ioutil deprecation (#110)

Author: jesusfcr

pkg/api/test/utils.go

@@ -7,7 +7,7 @@ package test
 import (
 	"bytes"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http/httptest"
 	"testing"
 
@@ -52,7 +52,7 @@ type RequestBody struct {
 
 // JSONObject retrieves a JSON object from a ResponseRecorder into a struct or fails the test.
 func JSONObject(t *testing.T, rec *httptest.ResponseRecorder, field string, element interface{}) {
-	body, err := ioutil.ReadAll(rec.Body)
+	body, err := io.ReadAll(rec.Body)
 	if err != nil {
 		t.Error(err)
 	}