Update anthropic construction

Author: Kludex

pydantic_ai_slim/pydantic_ai/providers/gateway.py

@@ -7,12 +7,12 @@
 from urllib.parse import urljoin
 
 import httpx
-from anthropic import AsyncAnthropic
 
 from pydantic_ai.exceptions import UserError
 from pydantic_ai.models import Model, cached_async_http_client, get_user_agent
 
 if TYPE_CHECKING:
+    from anthropic import AsyncAnthropic
     from google.genai import Client as GoogleClient
     from groq import AsyncGroq
     from openai import AsyncOpenAI
@@ -106,9 +106,9 @@ def gateway_provider(
 
         return AnthropicProvider(
             anthropic_client=AsyncAnthropic(
+                auth_token=api_key,
                 base_url=urljoin(base_url, 'anthropic'),
                 http_client=http_client,
-                default_headers={'Authorization': api_key},
             )
         )
     elif upstream_provider == 'google-vertex':

tests/providers/cassettes/test_gateway/test_gateway_provider_with_anthropic.yaml

@@ -40,7 +40,7 @@ interactions:
       content:
       - text: The capital of France is Paris.
         type: text
-      id: msg_014JDheu3y78eUkXc8faaVUx
+      id: msg_015tco2dv5oh9rFq1PcZAduv
       model: claude-3-5-sonnet-20241022
       role: assistant
       stop_reason: end_turn