[Python] Error deploying django/python app to Heroku - 'Error with requirements to build wheel'

I am trying to deploy my Django app to Heroku. I get the following error output:

Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'error'
error: subprocess-exited-with-error

× Getting requirements to build wheel did not run successfully.
│ exit code: 1
╰─> [24 lines of output]
Traceback (most recent call last):
File "/app/.heroku/python/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 353, in <module>
main()
~~~~^^
File "/app/.heroku/python/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 335, in main
json_out['return_val'] = hook(**hook_input['kwargs'])
~~~~^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/.heroku/python/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 118, in get_requires_for_build_wheel
return hook(config_settings)
File "/tmp/pip-build-env-zgoqdfmt/overlay/lib/python3.13/site-packages/setuptools/build_meta.py", line 334, in get_requires_for_build_wheel
return self._get_build_requires(config_settings, requirements=[])
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/tmp/pip-build-env-zgoqdfmt/overlay/lib/python3.13/site-packages/setuptools/build_meta.py", line 304, in _get_build_requires
self.run_setup()
~~~~~~~~~~~~~~^^
File "/tmp/pip-build-env-zgoqdfmt/overlay/lib/python3.13/site-packages/setuptools/build_meta.py", line 522, in run_setup
super().run_setup(setup_script=setup_script)
~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/tmp/pip-build-env-zgoqdfmt/overlay/lib/python3.13/site-packages/setuptools/build_meta.py", line 320, in run_setup
exec(code, locals())
~~~~^^^^^^^^^^^^^^^^
File "<string>", line 29, in <module>
File "<string>", line 26, in get_version
KeyError: '__version__'
[end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× Getting requirements to build wheel did not run successfully.
│ exit code: 1
╰─> See above for output.

note: This error originates from a subprocess, and is likely not a problem with pip.
! Error: Unable to install dependencies using pip.
!
! See the log output above for more information.
! Push rejected, failed to compile Python app.
! Push failed


I have tried upgrading Wheel and Setup Tools from a similar Stack Overflow thread but it does not fix the problem. Any ideas what the problem could be?

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