Enable UP007 in pyupgrade and update type hints (#4937)

Author: vidipsingh

pyproject.toml

@@ -208,7 +208,6 @@ ignore = [
     "RET506",      # Unnecessary `elif`
     "B018",        # Found useless expression
     "RUF002",      # Docstring contains ambiguous
-    "UP007",       # For pyupgrade
 ]
 
 [tool.ruff.lint.per-file-ignores]

src/pybamm/expression_tree/concatenations.py

@@ -1,10 +1,11 @@
+from __future__ import annotations
+
 #
 # Concatenation classes
 #
 from __future__ import annotations
 import copy
 from collections import defaultdict
-from typing import Optional
 
 import numpy as np
 import numpy.typing as npt
@@ -470,7 +471,7 @@ def _concatenation_new_copy(self, children, perform_simplifications=True):
 class ConcatenationVariable(Concatenation):
     """A Variable representing a concatenation of variables."""
 
-    def __init__(self, *children, name: Optional[str] = None):
+    def __init__(self, *children, name: str | None = None):
         if name is None:
             # Name is the intersection of the children names (should usually make sense
             # if the children have been named consistently)
@@ -526,7 +527,7 @@ def intersect(s1: str, s2: str):
     return intersect.lstrip().rstrip()
 
 
-def simplified_concatenation(*children, name: Optional[str] = None):
+def simplified_concatenation(*children, name: str | None = None):
     """Perform simplifications on a concatenation."""
     # remove children that are None
     children = list(filter(lambda x: x is not None, children))
@@ -556,7 +557,7 @@ def simplified_concatenation(*children, name: Optional[str] = None):
             return concat
 
 
-def concatenation(*children, name: Optional[str] = None):
+def concatenation(*children, name: str | None = None):
     """Helper function to create concatenations."""
     # TODO: add option to turn off simplifications
     return simplified_concatenation(*children, name=name)