fix: Address PR review comments

- Change Crew.verbose field type from bool to bool | None to allow env var check
- Remove unused imports (StringIO, pytest) from test file

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

lib/crewai/src/crewai/crew.py

@@ -193,7 +193,13 @@ class Crew(FlowTrackable, BaseModel):
     tasks: list[Task] = Field(default_factory=list)
     agents: list[BaseAgent] = Field(default_factory=list)
     process: Process = Field(default=Process.sequential)
-    verbose: bool = Field(default=False)
+    verbose: bool | None = Field(
+        default=None,
+        description=(
+            "Whether to enable verbose logging output. True=always enable, "
+            "False=always disable, None=check CREWAI_VERBOSE env var (defaults to True if not set)."
+        ),
+    )
     memory: bool = Field(
         default=False,
         description="If crew should use memory to store memories of it's execution",

lib/crewai/tests/test_verbose_control.py

@@ -1,11 +1,8 @@
 """Test verbose control for Flow and Crew."""
 
 import os
-from io import StringIO
 from unittest.mock import patch
 
-import pytest
-
 from crewai.events.event_listener import EventListener
 from crewai.flow.flow import Flow, start, listen
 from crewai.utilities.logger_utils import should_enable_verbose