remove several internal-only methods from offsets.pyi (#1163)

Author: MarcoGorelli

pandas-stubs/_libs/tslibs/offsets.pyi

@@ -26,8 +26,6 @@ from pandas.tseries.holiday import AbstractHolidayCalendar
 _DatetimeT = TypeVar("_DatetimeT", bound=datetime)
 _TimedeltaT = TypeVar("_TimedeltaT", bound=timedelta)
 
-prefix_mapping: dict[str, type]
-
 class ApplyTypeError(TypeError): ...
 
 class BaseOffset:
@@ -96,9 +94,6 @@ class BaseOffset:
     def __getstate__(self): ...
     @property
     def nanos(self) -> int: ...
-    def onOffset(self, dt: datetime) -> bool: ...
-    def isAnchored(self) -> bool: ...
-    def is_anchored(self) -> bool: ...
 
 class SingleConstructorOffset(BaseOffset):
     def __reduce__(self): ...
@@ -110,8 +105,6 @@ class Tick(SingleConstructorOffset):
     @property
     def nanos(self) -> int: ...
 
-def delta_to_tick(delta: timedelta) -> Tick: ...
-
 class Day(Tick): ...
 class Hour(Tick): ...
 class Minute(Tick): ...
@@ -123,19 +116,14 @@ class Nano(Tick): ...
 class RelativeDeltaOffset(BaseOffset):
     def __init__(self, n: int = ..., normalize: bool = ..., **kwds: Any) -> None: ...
 
-class BusinessMixin(SingleConstructorOffset):
-    def __init__(
-        self, n: int = ..., normalize: bool = ..., offset: timedelta = ...
-    ) -> None: ...
-
 # Changed from implementation because it is not allowed for `PeriodDtype`
 class BusinessDay(BaseOffset):
     def __init__(
         self, n: int = ..., normalize: bool = ..., offset: timedelta = ...
     ) -> None: ...
     def __reduce__(self): ...
 
-class BusinessHour(BusinessMixin):
+class BusinessHour(SingleConstructorOffset):
     def __init__(
         self,
         n: int = ...,
@@ -209,7 +197,7 @@ class FY5253(FY5253Mixin): ...
 class FY5253Quarter(FY5253Mixin): ...
 class Easter(SingleConstructorOffset): ...
 
-class _CustomBusinessMonth(BusinessMixin):
+class _CustomBusinessMonth(SingleConstructorOffset):
     def __init__(
         self,
         n: int = ...,
@@ -274,10 +262,3 @@ BMonthBegin = BusinessMonthBegin
 CBMonthEnd = CustomBusinessMonthEnd
 CBMonthBegin = CustomBusinessMonthBegin
 CDay = CustomBusinessDay
-
-def roll_qtrday(
-    other: datetime, n: int, month: int, day_opt: str, modby: int
-) -> int: ...
-def shift_months(
-    dtindex: npt.NDArray[np.int64], months: int, day_opt: str | None = ...
-) -> npt.NDArray[np.int64]: ...