feat: support baggage propagation in httpc (#2375)

* feat: support baggage propagation in httpc

* chore: use go 1.16

* chore: use go 1.16

* chore: use go ^1.16

* chore: remove deprecated

core/iox/read.go

@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"bytes"
 	"io"
-	"io/ioutil"
 	"os"
 	"strings"
 )
@@ -26,7 +25,7 @@ type (
 func DupReadCloser(reader io.ReadCloser) (io.ReadCloser, io.ReadCloser) {
 	var buf bytes.Buffer
 	tee := io.TeeReader(reader, &buf)
-	return ioutil.NopCloser(tee), ioutil.NopCloser(&buf)
+	return io.NopCloser(tee), io.NopCloser(&buf)
 }
 
 // KeepSpace customizes the reading functions to keep leading and tailing spaces.
@@ -54,7 +53,7 @@ func ReadBytes(reader io.Reader, buf []byte) error {
 
 // ReadText reads content from the given file with leading and tailing spaces trimmed.
 func ReadText(filename string) (string, error) {
-	content, err := ioutil.ReadFile(filename)
+	content, err := os.ReadFile(filename)
 	if err != nil {
 		return "", err
 	}