Export from pyproject.toml doesn't include "extras"

[wgordon17]

• I have searched the issue tracker and believe that this is not a duplicate.

Steps to reproduce

$ pdm init --non-interactive
$ pdm add dynaconf[vault]
$ pdm export --without-hashes --pyproject -v

Actual behavior

dynaconf>=3.1.12

Expected behavior

dynaconf[vault]>=3.1.12

Environment Information

PDM version:
  2.4.8
Python Interpreter:
  /Users/wgordon/test-project/.venv/bin/python (3.11)
Project Root:
  /Users/wgordon/test-project
Project Packages:
  None
{
  "implementation_name": "cpython",
  "implementation_version": "3.11.2",
  "os_name": "posix",
  "platform_machine": "arm64",
  "platform_release": "22.3.0",
  "platform_system": "Darwin",
  "platform_version": "Darwin Kernel Version 22.3.0: Mon Jan 30 20:38:37 PST 2023; root:xnu-8792.81.3~2/RELEASE_ARM64_T6000",
  "python_full_version": "3.11.2",
  "platform_python_implementation": "CPython",
  "python_version": "3.11",
  "sys_platform": "darwin"
}

[wgordon17]

Brilliantly quick, thanks!