assert failure when wheel has no arch?

[cbm755]

I ran:

 req2flatpak --requirements \
         platformdirs==4.3.6 \
         --target-platforms "311-x86_64 311-aarch64" --outfile python3-platformdirs.yaml

Traceback (most recent call last):
  File "/home/cbm/.local/bin/req2flatpak", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/cbm/.local/lib/python3.12/site-packages/req2flatpak.py", line 741, in main
    PlatformFactory.from_string(platform) for platform in options.target_platforms
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/cbm/.local/lib/python3.12/site-packages/req2flatpak.py", line 264, in from_string
    return cls.from_python_version_and_arch(minor_version=int(minor), arch=arch)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/cbm/.local/lib/python3.12/site-packages/req2flatpak.py", line 286, in from_python_version_and_arch
    assert arch in ["x86_64", "aarch64"]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

I assume this is because the wheel is not arch-specific. Here's the yaml from an older version of req2flatpak, not sure which one, b/c we don't record version info.

# Generated by req2flatpak.py --requirements platformdirs==4.2.2 --target-platforms 311-x86_64 311-aarch64 --outfile python3-platformdirs.yaml
name: python3-package-installation
buildsystem: simple
build-commands:
- pip3 install --verbose --exists-action=i --no-index --find-links="file://${PWD}"
  --prefix=${FLATPAK_DEST} --no-build-isolation platformdirs
sources:
- type: file
  url: https://files.pythonhosted.org/packages/68/13/2aa1f0e1364feb2c9ef45302f387ac0bd81484e9c9a4c5688a322fbdfd08/platformdirs-4.2.2-py3-none-any.whl
  sha256: 2d7a1657e36a80ea911db832a8a6ece5ee53d8de21edd5cc5879af6530b1bfee