Add execution_image parameter to Agent for custom Docker images

- Add execution_image field to Agent class for specifying custom Docker images
- Modify get_code_execution_tools() to pass custom image to CodeInterpreterTool
- Add comprehensive tests for the new functionality
- Update documentation with usage examples
- Fixes #2933: Allow customizing CrewAI code executor Docker image

Co-Authored-By: João <joao@crewai.com>

tests/test_custom_execution_image_integration.py

@@ -0,0 +1,36 @@
+import pytest
+from unittest.mock import patch, MagicMock
+from crewai import Agent, Task, Crew
+
+
+@patch('crewai_tools.CodeInterpreterTool')
+def test_crew_with_custom_execution_image_integration(mock_code_interpreter_class):
+    """Integration test for custom execution image in a Crew workflow."""
+    mock_tool_instance = MagicMock()
+    mock_code_interpreter_class.return_value = mock_tool_instance
+    
+    agent = Agent(
+        role="Python Developer",
+        goal="Execute Python code",
+        backstory="Expert in Python programming",
+        allow_code_execution=True,
+        execution_image="python:3.11-slim"
+    )
+    
+    task = Task(
+        description="Calculate 2 + 2",
+        expected_output="The result of 2 + 2",
+        agent=agent
+    )
+    
+    crew = Crew(
+        agents=[agent],
+        tasks=[task]
+    )
+    
+    tools = crew._prepare_tools(task, agent)
+    
+    mock_code_interpreter_class.assert_called_with(
+        unsafe_mode=False,
+        default_image_tag="python:3.11-slim"
+    )