Add unit property to Timestamp

Author: skatsuta

pandas-stubs/_libs/tslibs/timestamps.pyi

@@ -310,3 +310,5 @@ class Timestamp(datetime):
     def days_in_month(self) -> int: ...
     @property
     def daysinmonth(self) -> int: ...
+    @property
+    def unit(self) -> str: ...

tests/test_scalars.py

@@ -1189,6 +1189,7 @@ def test_timestamp_properties() -> None:
     check(assert_type(ts.tzinfo, Optional[dt.tzinfo]), type(None))
     check(assert_type(ts.value, int), int)
     check(assert_type(ts.year, int), int)
+    check(assert_type(ts.unit, str), str)
 
 
 def test_timestamp_add_sub() -> None: