Standardize warnings with WARNING ⚠️ ... (#9467)

* Standardize warnings

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

utils/__init__.py

@@ -4,9 +4,15 @@ utils/initialization
 """
 
 import contextlib
+import platform
 import threading
 
 
+def emojis(str=''):
+    # Return platform-dependent emoji-safe version of string
+    return str.encode().decode('ascii', 'ignore') if platform.system() == 'Windows' else str
+
+
 class TryExcept(contextlib.ContextDecorator):
     # YOLOv5 TryExcept class. Usage: @TryExcept() decorator or 'with TryExcept():' context manager
     def __init__(self, msg=''):
@@ -17,7 +23,7 @@ class TryExcept(contextlib.ContextDecorator):
 
     def __exit__(self, exc_type, value, traceback):
         if value:
-            print(f'{self.msg}{value}')
+            print(emojis(f'{self.msg}{value}'))
         return True
 
 
@@ -38,7 +44,7 @@ def notebook_init(verbose=True):
     import os
     import shutil
 
-    from utils.general import check_font, check_requirements, emojis, is_colab
+    from utils.general import check_font, check_requirements, is_colab
     from utils.torch_utils import select_device  # imports
 
     check_requirements(('psutil', 'IPython'))