Fix type checking for pytask.mark.x. (#432)

Author: tobiasraabe

docs/source/changes.md

@@ -50,6 +50,7 @@ releases are available on [PyPI](https://pypi.org/project/pytask) and
   exception. Now, it is easy to see which tasks are affected.
 - {pull}`430` updates some parts of the documentation.
 - {pull}`431` enables colors for WSL.
+- {pull}`432` fixes type checking of `pytask.mark.xxx`.
 
 ## 0.3.2 - 2023-06-07
 

src/_pytask/mark/__init__.pyi

@@ -5,7 +5,6 @@ from _pytask.mark.expression import Expression
 from _pytask.mark.expression import ParseError
 from _pytask.mark.structures import Mark
 from _pytask.mark.structures import MarkDecorator
-from _pytask.mark.structures import MarkGenerator
 from _pytask.tree_util import PyTree
 
 from _pytask.session import Session
@@ -14,7 +13,7 @@ import networkx as nx
 def select_by_keyword(session: Session, dag: nx.DiGraph) -> set[str]: ...
 def select_by_mark(session: Session, dag: nx.DiGraph) -> set[str]: ...
 
-class MARK_GEN:  # noqa: N801
+class MarkGenerator:
     @deprecated(
         "'@pytask.mark.produces' is deprecated starting pytask v0.4.0 and will be removed in v0.5.0. To upgrade your project to the new syntax, read the tutorial on product and dependencies: https://tinyurl.com/yrezszr4.",  # noqa: E501, PYI053
         category=FutureWarning,
@@ -42,6 +41,9 @@ class MARK_GEN:  # noqa: N801
         kwargs: dict[Any, Any] | None = None,
         produces: PyTree[Any] = None,
     ) -> None: ...
+    def __getattr__(self, name: str) -> MarkDecorator | Any: ...
+
+MARK_GEN = MarkGenerator()
 
 __all__ = [
     "Expression",