[zheng-guannan577]

Closes #823: #823

Typing gap

DateTime.diff() previously declared its parameter as datetime.datetime | None. Passing a Pendulum DateTime (the library's own datetime type, and the type diff() is documented to compare) could therefore be flagged by type checkers/linters, even though it works at runtime.

Change

In src/pendulum/datetime.py only, widen the parameter type to:

def diff(self, dt: DateTime | datetime.datetime | None = None, abs: bool = True) -> Interval[datetime.datetime]:

This is a typing-only change. No runtime logic, no other files, and no behaviour change.

Verification (honest note)

Full repo pytest was NOT run locally, because local 3.3.0 needs a Rust extension built with cargo which is not installed. No local test run is claimed beyond the GitHub web editor view; CI must verify the full test suite and typing.

• Added tests for changed code (not applicable: typing-only change, no runtime behaviour change)
• Updated documentation for changed code (not applicable: typing-only change)