Fix unreliable floating point equality (RUF069)

[alexfikl]

This just adds some ignores since both places seemed to want to compare actual equality.

[alexfikl]

Not quite sure where the pyright errors came from (new immutabledict?), but they seem ignorable:

 /home/runner/work/arraycontext/arraycontext/arraycontext/impl/pytato/outline.py:102:12 - error: Type "immutabledict[tuple[SerializationKey, ...], object]" is not assignable to return type "immutabledict[tuple[SerializationKey, ...], Array]"
  "immutabledict[tuple[SerializationKey, ...], object]" is not assignable to "immutabledict[tuple[SerializationKey, ...], Array]"
    Type parameter "_V@immutabledict" is covariant, but "object" is not a subtype of "Array"
      "object" is not assignable to "Array" (reportReturnType)
Error: Type "immutabledict[tuple[SerializationKey, ...], object]" is not assignable to return type "immutabledict[tuple[SerializationKey, ...], Array]"
  "immutabledict[tuple[SerializationKey, ...], object]" is not assignable to "immutabledict[tuple[SerializationKey, ...], Array]"
    Type parameter "_V@immutabledict" is covariant, but "object" is not a subtype of "Array"
      "object" is not assignable to "Array" (reportReturnType)
/home/runner/work/arraycontext/arraycontext/arraycontext/impl/pytato/outline.py:194:16 - warning: Return type, "immutabledict[str, Unknown]", is partially unknown (reportUnknownVariableType)
Warning: Return type, "immutabledict[str, Unknown]", is partially unknown (reportUnknownVariableType)
/home/runner/work/arraycontext/arraycontext/arraycontext/impl/pytato/outline.py:194:30 - warning: Argument type is partially unknown
  Argument corresponds to parameter "map" in function "__new__"
  Argument type is "dict[Unknown, Unknown]" (reportUnknownArgumentType)
Warning: Argument type is partially unknown
  Argument corresponds to parameter "map" in function "__new__"
  Argument type is "dict[Unknown, Unknown]" (reportUnknownArgumentType)