refactor(typing): Remove CompliantDataFrame.collect (#3041)

Noticed ahead of #2713

Author: dangotbanned

narwhals/_compliant/dataframe.py

@@ -155,9 +155,6 @@ def schema(self) -> Mapping[str, DType]: ...
     @property
     def shape(self) -> tuple[int, int]: ...
     def clone(self) -> Self: ...
-    def collect(
-        self, backend: _EagerAllowedImpl | None, **kwargs: Any
-    ) -> CompliantDataFrameAny: ...
     def collect_schema(self) -> Mapping[str, DType]: ...
     def drop(self, columns: Sequence[str], *, strict: bool) -> Self: ...
     def drop_nulls(self, subset: Sequence[str] | None) -> Self: ...