Update syntax to support recipe attribute confirm("prompt")

[lokkju]

Justfile supports the recipe attribute [confirm("prompt")] since at least 1.23.0. Attempting to use this attribute shows as a language syntax error

Example:

[confirm("echo foo?")]
foo:
    echo "foo"

Result: `

Reference: https://just.systems/man/en/chapter_32.html

[TTiger]

+1 having same issue

[nandorholozsnyak]

+1 here. Group syntax is also not supported (yet). That would be helpful.