Description

• Part of Replace typing hints with new version #3481
• Replaces legacy typing imports (Dict, Optional, Sequence, Tuple, Union) with the newer syntax (X | Y, X | None, dict, tuple) in ignite/engine/__init__.py.
• Moves Sequence to collections.abc

Changes

• Moved Sequence import from typing to collections.abc
• Removed Dict, Optional, Tuple, Union from typing imports
• Replaced all Optional[X] → X | None
• Replaced all Union[A, B] → A | B
• Replaced Dict → dict, Tuple → tuple

Checklist

• I have read the Contributing Guide
• My changes are consistent with the Guidelines