refactor: move from io/ioutil to io and os packages (#1546)

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

controllers/logo.go

@@ -1,8 +1,8 @@
 package controllers
 
 import (
-	"io/ioutil"
 	"net/http"
+	"os"
 	"path/filepath"
 	"strconv"
 
@@ -94,5 +94,5 @@ func writeBytesAsImage(data []byte, contentType string, w http.ResponseWriter, c
 }
 
 func getImage(path string) ([]byte, error) {
-	return ioutil.ReadFile(path) // nolint
+	return os.ReadFile(path) // nolint
 }