Implement CrewAIBaseModel and Update to ConfigDict (#29)

New CrewAIBaseModel:

Base for Agent, Crew, Task.
Includes generated, frozen UUID.
Adds hashing capability
Migrate to ConfigDict:

Replaces class Config with model_config, see this deprecation note .
Benefits:
Adds auditing capability with frozen UUIDs.

crewai/base/model.py

@@ -0,0 +1,24 @@
+import uuid
+from typing import Optional
+
+from pydantic import UUID4, BaseModel, Field, field_validator
+from pydantic_core import PydanticCustomError
+
+
+class CrewAIBaseModel(BaseModel):
+    """Base model with unique identifier."""
+
+    __hash__ = object.__hash__
+    id: UUID4 = Field(
+        default_factory=uuid.uuid4,
+        frozen=True,
+        description="Unique identifier for the object, not set by user.",
+    )
+
+    @field_validator("id", mode="before")
+    @classmethod
+    def _deny_user_set_id(cls, v: Optional[UUID4]) -> None:
+        if v:
+            raise PydanticCustomError(
+                "may_not_set_field", "This field is not to be set by the user.", {}
+            )