Added content-length header

Author: mkherlakian

.gitignore

@@ -7,3 +7,5 @@ coverage.txt
 /hookdeck-linux
 /hookdeck-windows.exe
 default_cassette.yaml
+.vscode/
+__debug_bin

pkg/proxy/proxy.go

@@ -233,14 +233,17 @@ func (p *Proxy) processAttempt(msg websocket.IncomingMessage) {
 				}
 			}
 		}
-
+	
 		if bodyIsText {
 			req.Body = ioutil.NopCloser(strings.NewReader(webhookEvent.Body.Request.DataString))
+			req.ContentLength = int64(len(webhookEvent.Body.Request.DataString))
 		} else {
 			req.Body = io.NopCloser(bytes.NewBuffer(webhookEvent.Body.Request.Data))
+			req.ContentLength = int64(len(webhookEvent.Body.Request.Data))
 		}
 
 		res, err := client.Do(req)
+
 		if err != nil {
 			color := ansi.Color(os.Stdout)
 			localTime := time.Now().Format(timeLayout)