Go deps upgrade, from ioutil to io (#14737)

* ioutil to io

* Update CHANGELOG.md

---------

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

CHANGELOG.md

@@ -19,6 +19,7 @@ The format is based on Keep a Changelog, and this project adheres to Semantic Ve
 - Process light client finality updates only for new finalized epochs instead of doing it for every block.
 - Refactor subnets subscriptions.
 - Refactor RPC handlers subscriptions.
+- Go deps upgrade, from `ioutil` to `io`
 
 ### Deprecated
 

testing/middleware/engine-api-proxy/proxy.go

@@ -9,7 +9,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"strings"
@@ -240,7 +239,7 @@ func (p *Proxy) sendHttpRequest(req *http.Request, requestBytes []byte) (*http.R
 	}
 
 	// Set the modified request as the proxy request body.
-	proxyReq.Body = ioutil.NopCloser(bytes.NewBuffer(requestBytes))
+	proxyReq.Body = io.NopCloser(bytes.NewBuffer(requestBytes))
 
 	// Required proxy headers for forwarding JSON-RPC requests to the execution client.
 	proxyReq.Header.Set("Host", req.Host)
@@ -261,14 +260,14 @@ func (p *Proxy) sendHttpRequest(req *http.Request, requestBytes []byte) (*http.R
 
 // Peek into the bytes of an HTTP request's body.
 func parseRequestBytes(req *http.Request) ([]byte, error) {
-	requestBytes, err := ioutil.ReadAll(req.Body)
+	requestBytes, err := io.ReadAll(req.Body)
 	if err != nil {
 		return nil, err
 	}
 	if err = req.Body.Close(); err != nil {
 		return nil, err
 	}
-	req.Body = ioutil.NopCloser(bytes.NewBuffer(requestBytes))
+	req.Body = io.NopCloser(bytes.NewBuffer(requestBytes))
 	return requestBytes, nil
 }