web-ontogpt requires python-multipart

[caufieldjh]

After fixing #475, web-ontogpt raises this error:

~/ontogpt$ web-ontogpt
ERROR:fastapi:Form data requires "python-multipart" to be installed.
You can install "python-multipart" with:

pip install python-multipart

Traceback (most recent call last):
  File "/home/harry/ontogpt/.venv/bin/web-ontogpt", line 3, in <module>
    from ontogpt.webapp.main import start
  File "/home/harry/ontogpt/src/ontogpt/webapp/main.py", line 71, in <module>
    def form_post(
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/routing.py", line 994, in decorator
    self.add_api_route(
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/routing.py", line 933, in add_api_route
    route = route_class(
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/routing.py", line 554, in __init__
    self.dependant = get_dependant(path=self.path_format, call=self.endpoint)
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/dependencies/utils.py", line 285, in get_dependant
    param_details = analyze_param(
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/dependencies/utils.py", line 482, in analyze_param
    ensure_multipart_is_installed()
  File "/home/harry/ontogpt/.venv/lib/python3.10/site-packages/fastapi/dependencies/utils.py", line 115, in ensure_multipart_is_installed
    raise RuntimeError(multipart_not_installed_error) from None
RuntimeError: Form data requires "python-multipart" to be installed.
You can install "python-multipart" with:

pip install python-multipart

This may be because multipart used to import python-multipart but this has changed (see fastapi/fastapi#5144 (comment)).