fixed pivot_table sort argument in pandas_stubs (#1077)

* fixed pivot_table sort argument in pandas_stubs

* fixed pivot_table argument and test_pivot_table

* replaced single-quote with double

* applied pre-commit hooks formated lint code

pandas-stubs/core/frame.pyi

@@ -1295,6 +1295,7 @@ class DataFrame(NDFrame, OpsMixin):
         dropna: _bool = ...,
         margins_name: _str = ...,
         observed: _bool = ...,
+        sort: _bool = ...,
     ) -> DataFrame: ...
     @overload
     def stack(

tests/test_frame.py

@@ -1088,6 +1088,17 @@ def test_types_pivot_table() -> None:
     )
 
 
+def test_pivot_table_sort():
+    df = pd.DataFrame({"a": [1, 2], "b": [3, 4], "c": [5, 6], "d": [7, 8]})
+
+    check(
+        assert_type(
+            df.pivot_table(values="a", index="b", columns="c", sort=True), pd.DataFrame
+        ),
+        pd.DataFrame,
+    )
+
+
 def test_types_groupby_as_index() -> None:
     """Test type of groupby.size method depending on `as_index`."""
     df = pd.DataFrame({"a": [1, 2, 3]})