Migrates ignite/metrics/fbeta.py from legacy typing syntax to Python 3.10+ union operators per #3481.

Changes

• Optional[X] → X | None (function parameters and cast calls)
• Union[str, torch.device] → str | torch.device (in cast expressions)
• Removed unused Optional and Union imports from typing module

Example

# Before
def Fbeta(
    precision: Optional[Precision] = None,
    device: Optional[Union[str, torch.device]] = None,
) -> MetricsLambda:
    ...

# After
def Fbeta(
    precision: Precision | None = None,
    device: str | torch.device | None = None,
) -> MetricsLambda:
    ...

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.