feat: async llm support

feat: introduce async contract to BaseLLM

feat: add async call support for:

Azure provider

Anthropic provider

OpenAI provider

Gemini provider

Bedrock provider

LiteLLM provider

chore: expand scrubbed header fields (conftest, anthropic, bedrock)

chore: update docs to cover async functionality

chore: update and harden tests to support acall; re-add uri for cassette compatibility

chore: generate missing cassette

fix: ensure acall is non-abstract and set supports_tools = true for supported Anthropic models

chore: improve Bedrock async docstring and general test robustness

lib/crewai/tests/test_custom_llm.py

@@ -77,6 +77,9 @@ class CustomLLM(BaseLLM):
         """
         return 4096
 
+    async def acall(self, messages, tools=None, callbacks=None, available_functions=None, from_task=None, from_agent=None, response_model=None):
+        raise NotImplementedError
+
 
 @pytest.mark.vcr()
 def test_custom_llm_implementation():
@@ -192,6 +195,9 @@ class JWTAuthLLM(BaseLLM):
         """Return a default context window size."""
         return 8192
 
+    async def acall(self, messages, tools=None, callbacks=None, available_functions=None, from_task=None, from_agent=None, response_model=None):
+        raise NotImplementedError
+
 
 def test_custom_llm_with_jwt_auth():
     """Test a custom LLM implementation with JWT authentication."""
@@ -339,6 +345,9 @@ class TimeoutHandlingLLM(BaseLLM):
         """
         return 8192
 
+    async def acall(self, messages, tools=None, callbacks=None, available_functions=None, from_task=None, from_agent=None, response_model=None):
+        raise NotImplementedError
+
 
 def test_timeout_handling_llm():
     """Test a custom LLM implementation with timeout handling and retry logic."""