Add base_url to Mistral Provider (#1617)

Author: alibeyram

docs/models/mistral.md

@@ -52,7 +52,7 @@ from pydantic_ai.models.mistral import MistralModel
 from pydantic_ai.providers.mistral import MistralProvider
 
 model = MistralModel(
-    'mistral-large-latest', provider=MistralProvider(api_key='your-api-key')
+    'mistral-large-latest', provider=MistralProvider(api_key='your-api-key', base_url='https://<mistral-provider-endpoint>')
 )
 agent = Agent(model)
 ...

pydantic_ai_slim/pydantic_ai/providers/mistral.py

@@ -44,6 +44,7 @@ def __init__(
         *,
         api_key: str | None = None,
         mistral_client: Mistral | None = None,
+        base_url: str | None = None,
         http_client: AsyncHTTPClient | None = None,
     ) -> None:
         """Create a new Mistral provider.
@@ -52,11 +53,13 @@ def __init__(
             api_key: The API key to use for authentication, if not provided, the `MISTRAL_API_KEY` environment variable
                 will be used if available.
             mistral_client: An existing `Mistral` client to use, if provided, `api_key` and `http_client` must be `None`.
+            base_url: The base url for the Mistral requests.
             http_client: An existing async client to use for making HTTP requests.
         """
         if mistral_client is not None:
             assert http_client is None, 'Cannot provide both `mistral_client` and `http_client`'
             assert api_key is None, 'Cannot provide both `mistral_client` and `api_key`'
+            assert base_url is None, 'Cannot provide both `mistral_client` and `base_url`'
             self._client = mistral_client
         else:
             api_key = api_key or os.environ.get('MISTRAL_API_KEY')
@@ -67,7 +70,7 @@ def __init__(
                     'to use the Mistral provider.'
                 )
             elif http_client is not None:
-                self._client = Mistral(api_key=api_key, async_client=http_client)
+                self._client = Mistral(api_key=api_key, async_client=http_client, server_url=base_url)
             else:
                 http_client = cached_async_http_client(provider='mistral')
-                self._client = Mistral(api_key=api_key, async_client=http_client)
+                self._client = Mistral(api_key=api_key, async_client=http_client, server_url=base_url)