Refactor Codebase to Use Pydantic v2 and Enhance Type Hints, Documentation (#24)

Update to Pydantic v2:

Transitioned all references from pydantic.v1 to pydantic (v2), ensuring compatibility with the latest Pydantic features and improvements.
Affected components include agent tools, prompts, crew, and task modules.
Refactoring & Alignment with Pydantic Standards:

Refactored the agent module away from traditional __init__ to align more closely with Pydantic best practices.
Updated the crew module to Pydantic v2 and enhanced configurations, allowing JSON and dictionary inputs. Additionally, some (not all) exceptions have been migrated to leverage Pydantic's error-handling capabilities.
Enhancements to Validators and Typings:

Improved validators and type annotations across multiple modules, enhancing code readability and maintainability.
Streamlined the validation process in line with Pydantic v2's methodologies.
Import and Configuration Adjustments:

Updated to test-related absolute imports due to issues with Pytest finding packages through relative imports.

crewai/crew.py

@@ -1,7 +1,8 @@
 import json
-from typing import List, Optional
+from typing import Any, Dict, List, Optional, Union
 
-from pydantic.v1 import BaseModel, Field, Json, root_validator
+from pydantic import BaseModel, Field, Json, field_validator, model_validator
+from pydantic_core import PydanticCustomError
 
 from .agent import Agent
 from .process import Process
@@ -10,62 +11,69 @@ from .tools.agent_tools import AgentTools
 
 
 class Crew(BaseModel):
-    """
-    Class that represents a group of agents, how they should work together and
-    their tasks.
-    """
+    """Class that represents a group of agents, how they should work together and their tasks."""
 
-    tasks: Optional[List[Task]] = Field(description="List of tasks")
-    agents: Optional[List[Agent]] = Field(description="List of agents in this crew.")
+    tasks: List[Task] = Field(description="List of tasks", default_factory=list)
+    agents: List[Agent] = Field(
+        description="List of agents in this crew.", default_factory=list
+    )
     process: Process = Field(
         description="Process that the crew will follow.", default=Process.sequential
     )
     verbose: bool = Field(
         description="Verbose mode for the Agent Execution", default=False
     )
-    config: Optional[Json] = Field(
+    config: Optional[Union[Json, Dict[str, Any]]] = Field(
         description="Configuration of the crew.", default=None
     )
 
-    @root_validator(pre=True)
-    def check_config(_cls, values):
-        if not values.get("config") and (
-            not values.get("agents") and not values.get("tasks")
-        ):
-            raise ValueError("Either agents and task need to be set or config.")
+    @classmethod
+    @field_validator("config", mode="before")
+    def check_config_type(cls, v: Union[Json, Dict[str, Any]]):
+        if isinstance(v, Json):
+            return json.loads(v)
+        return v
 
-        if values.get("config"):
-            config = json.loads(values.get("config"))
-            if not config.get("agents") or not config.get("tasks"):
-                raise ValueError("Config should have agents and tasks.")
+    @model_validator(mode="after")
+    def check_config(self):
+        if not self.config and not self.tasks and not self.agents:
+            raise PydanticCustomError(
+                "missing_keys", "Either agents and task need to be set or config.", {}
+            )
 
-            values["agents"] = [Agent(**agent) for agent in config["agents"]]
+        if self.config:
+            if not self.config.get("agents") or not self.config.get("tasks"):
+                raise PydanticCustomError(
+                    "missing_keys_in_config", "Config should have agents and tasks", {}
+                )
+
+            self.agents = [Agent(**agent) for agent in self.config["agents"]]
 
             tasks = []
-            for task in config["tasks"]:
-                task_agent = [
-                    agt for agt in values["agents"] if agt.role == task["agent"]
-                ][0]
+            for task in self.config["tasks"]:
+                task_agent = [agt for agt in self.agents if agt.role == task["agent"]][
+                    0
+                ]
                 del task["agent"]
                 tasks.append(Task(**task, agent=task_agent))
 
-            values["tasks"] = tasks
-        return values
+            self.tasks = tasks
+        return self
 
     def kickoff(self) -> str:
-        """
-        Kickoff the crew to work on it's tasks.
-                Returns:
-                        output (List[str]): Output of the crew for each task.
+        """Kickoff the crew to work on its tasks.
+
+        Returns:
+            Output of the crew for each task.
         """
         if self.process == Process.sequential:
             return self.__sequential_loop()
 
     def __sequential_loop(self) -> str:
-        """
-        Loop that executes the sequential process.
-                Returns:
-                        output (str): Output of the crew.
+        """Loop that executes the sequential process.
+
+        Returns:
+            Output of the crew.
         """
         task_outcome = None
         for task in self.tasks: