Fix typo

server/ec2proxy_default.go

@@ -22,7 +22,7 @@ func StartEc2EndpointProxyServerProcess() error {
 		return err
 	}
 	time.Sleep(time.Second * 1)
-	if !isProxyRunning() {
+	if !IsProxyRunning() {
 		return errors.New("The EC2 Instance Metadata endpoint proxy server isn't running. Run `aws-vault proxy` as Administrator or root in the background and then try this command again")
 	}
 	return nil