Fix for 403 error on /meta endpoint

[assert0]

Add the Referer header to the client request to fix the following error:

Traceback (most recent call last):
  File "/usr/local/bin/speedtest-cli", line 7, in <module>
    sys.exit(main())
             ~~~~^^
  File "/usr/local/lib/python3.13/site-packages/click/core.py", line 1485, in __call__
    return self.main(*args, **kwargs)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/rich_click/rich_command.py", line 216, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.13/site-packages/click/core.py", line 1269, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/click/core.py", line 824, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.13/site-packages/speedtest_cloudflare_cli/main.py", line 110, in main
    "metadata": speedtester.metadata.__dict__,
                ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/speedtest_cloudflare_cli/core/speedtest.py", line 182, in metadata
    return metadata.Metadata.model_validate(client().get(f"{self.url}/meta").json())
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/pydantic/main.py", line 716, in model_validate
    return cls.__pydantic_validator__.validate_python(
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        obj,
        ^^^^
    ...<5 lines>...
        by_name=by_name,
        ^^^^^^^^^^^^^^^^
    )
    ^
pydantic_core._pydantic_core.ValidationError: 9 validation errors for Metadata
hostname
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
clientIp
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
httpProtocol
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
asn
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
asOrganization
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
colo
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
country
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
latitude
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
longitude
  Field required [type=missing, input_value={}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing

[takitsu21]

Hello @assert0 thanks for your contribution ! I will merge and deploy it asap