Benthos closes stdin when hot reloading a config with stdin input

[mihaitodor]

Given this config:

input:
  stdin: {}

If I run it via benthos -w -c foo.yaml and then I edit it and I insert a space in it or make any change to get Benthos to reload it, it ends up spewing the following error:

ERRO Failed to read message: read /dev/stdin: file already closed @service=benthos label="" path=root.input

This is happening with Benthos v4.0.0.