Cannot resolve dynamic version in pyproject.toml

[amolenaar]

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

Steps to reproduce

1. Check out the project https://github.com/amolenaar/meson-python-pdm-example
2. Run pdm install
3. See the error: [KeyError]: 'Version'

NB. This works fine with PDM 2.17.2.

Debug log

$ pdm install -v
STATUS: Resolving packages from lockfile...
unearth.preparer: The file . is a local directory, use it directly
pdm.termui: Running PEP 517 backend to get metadata for <Link file:///home/arjan/Development/meson-python-pdm-example (from None)>
pdm.termui: Preparing environment(Non-isolated mode) for PEP 517 build...
pdm.termui: Failed to build package, try parsing project files.
Traceback (most recent call last):
  File "/home/arjan/.local/bin/pdm", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/core.py", line 346, in main
    return core.main(args or sys.argv[1:])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/core.py", line 264, in main
    raise cast(Exception, err).with_traceback(traceback) from None
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/core.py", line 259, in main
    self.handle(project, options)
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/core.py", line 195, in handle
    command.handle(project, options)
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/cli/commands/install.py", line 103, in handle
    actions.do_sync(
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/cli/actions.py", line 330, in do_sync
    synchronizer.synchronize()
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/installers/synchronizers.py", line 341, in synchronize
    to_add, to_update, to_remove = self.compare_with_working_set()
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/installers/synchronizers.py", line 167, in compare_with_working_set
    candidates = self.candidates.copy()
                 ^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/functools.py", line 995, in __get__
    val = self.func(instance)
          ^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/installers/synchronizers.py", line 100, in candidates
    if self.should_install_editables():
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/installers/synchronizers.py", line 119, in should_install_editables
    metadata = self.self_candidate.prepare(self.environment).metadata
               ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/functools.py", line 995, in __get__
    val = self.func(instance)
          ^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/installers/synchronizers.py", line 88, in self_candidate
    return self.environment.project.make_self_candidate(not self.no_editable)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/project/core.py", line 543, in make_self_candidate
    can.prepare(self.environment).metadata
  File "/home/arjan/.local/pipx/venvs/pdm/lib64/python3.12/site-packages/pdm/models/candidates.py", line 602, in metadata
    self.candidate.version = result.version
                             ^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/importlib/metadata/__init__.py", line 467, in version
    return self.metadata['Version']
           ~~~~~~~~~~~~~^^^^^^^^^^^
KeyError: 'Version'

Actual behavior

An error. This looks like a regression, as it works fine with PDM 2.17.2.

Expected behavior

It should install the package, as it does with 2.17.2.

Environment Information

PDM version:
  2.17.3
Python Interpreter:
  .../meson-python-pdm-example/.venv/bin/python (3.12)
Project Root:
  .../meson-python-pdm-example
Local Packages:
  
{
  "implementation_name": "cpython",
  "implementation_version": "3.12.4",
  "os_name": "posix",
  "platform_machine": "x86_64",
  "platform_release": "6.9.11-200.fc40.x86_64",
  "platform_system": "Linux",
  "platform_version": "#1 SMP PREEMPT_DYNAMIC Thu Jul 25 18:17:34 UTC 2024",
  "python_full_version": "3.12.4",
  "platform_python_implementation": "CPython",
  "python_version": "3.12",
  "sys_platform": "linux"
}