Fix new mypy warnings

Some are from updated pyyaml typing and others are from mypy
0.990 being more careful with optional parameters.

python/lsst/pipe/base/connections.py

@@ -411,7 +411,7 @@ class attribute must match a function argument name in the ``run``
 
     dimensions: ClassVar[Set[str]]
 
-    def __init__(self, *, config: "PipelineTaskConfig" = None):
+    def __init__(self, *, config: "PipelineTaskConfig" | None = None):
         self.inputs: Set[str] = set(self.inputs)
         self.prerequisiteInputs: Set[str] = set(self.prerequisiteInputs)
         self.outputs: Set[str] = set(self.outputs)

python/lsst/pipe/base/pipelineIR.py

@@ -30,7 +30,19 @@
 from collections import Counter
 from collections.abc import Iterable as abcIterable
 from dataclasses import dataclass, field
-from typing import Any, Dict, Generator, List, Literal, Mapping, MutableMapping, Optional, Set, Union
+from typing import (
+    Any,
+    Dict,
+    Generator,
+    Hashable,
+    List,
+    Literal,
+    Mapping,
+    MutableMapping,
+    Optional,
+    Set,
+    Union,
+)
 
 import yaml
 from lsst.resources import ResourcePath, ResourcePathExpression
@@ -46,7 +58,7 @@ class PipelineYamlLoader(yaml.SafeLoader):
     found inside a pipeline file at a given scope.
     """
 
-    def construct_mapping(self, node: yaml.Node, deep: bool = False) -> Mapping[str, Any]:
+    def construct_mapping(self, node: yaml.MappingNode, deep: bool = False) -> dict[Hashable, Any]:
         # do the call to super first so that it can do all the other forms of
         # checking on this node. If you check the uniqueness of keys first
         # it would save the work that super does in the case of a failure, but

python/lsst/pipe/base/tests/simpleQGraph.py

@@ -274,7 +274,7 @@ def makeSimpleButler(root: str, run: str = "test", inMemory: bool = True) -> But
 
 
 def populateButler(
-    pipeline: Pipeline, butler: Butler, datasetTypes: Dict[Optional[str], List[str]] = None
+    pipeline: Pipeline, butler: Butler, datasetTypes: Dict[Optional[str], List[str]] | None = None
 ) -> None:
     """Populate data butler with data needed for test.