How do I get text within brackets with RegEx in Gdscript?

In c# this regex pattern shown below would exclude the brackets but in Gdscript it still includes the brackets:

var regex = RegEx.new()
var s = "[test] hello"
regex.compile("\\[(.*?)\\]")
var ID = regex.search(s).get_string().strip_edges()

How do I get "test" and not "[test]"?

This should get the first capturing group, which is the text inside the brackets:
var ID = regex.search(s).get_string(1).strip_edges()