Fix mypy failures

[Saransh-cpp]

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Mypy is failing with the error -

mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

glass/core/array.py:169: error: Unused "type: ignore" comment  [unused-ignore]
glass/core/array.py:169: error: Incompatible return value type (got "float64 | ndarray[tuple[int, ...], dtype[float64]]", expected "ndarray[tuple[int, ...], dtype[float64]]")  [return-value]
glass/core/array.py:169: note: Error code "return-value" not covered by "type: ignore" comment
glass/shells.py:239: error: Argument 1 has incompatible type "ndarray[tuple[int, ...], dtype[floating[Any]]]"; expected "Sequence[float] | ndarray[tuple[int, ...], dtype[float64]]"  [arg-type]
glass/shells.py:241: error: Argument 1 to "RadialWindow" has incompatible type "ndarray[tuple[int, ...], dtype[floating[Any]]]"; expected "ndarray[tuple[int, ...], dtype[float64]]"  [arg-type]
glass/shells.py:413: error: Incompatible return value type (got "tuple[ndarray[tuple[int, ...], dtype[Any]], ndarray[tuple[int, ...], dtype[floating[Any]]]]", expected "tuple[ndarray[tuple[int, ...], dtype[float64]], ndarray[tuple[int, ...], dtype[float64]]]")  [return-value]
glass/shells.py:568: error: Incompatible types in assignment (expression has type "ndarray[tuple[int, ...], dtype[floating[_64Bit]]]", variable has type "ndarray[tuple[int, ...], dtype[float64]]")  [assignment]
glass/shells.py:632: error: Incompatible types in assignment (expression has type "ndarray[tuple[int, ...], dtype[floating[_64Bit]]]", variable has type "ndarray[tuple[int, ...], dtype[float64]]")  [assignment]
glass/shells.py:676: error: Invalid index type "tuple[object, ...]" for "ndarray[tuple[int, ...], dtype[float64]]"; expected type "SupportsIndex | slice[Any, Any, Any] | EllipsisType | _SupportsArray[dtype[numpy.bool[builtins.bool]] | dtype[integer[Any]]] | _NestedSequence[_SupportsArray[dtype[numpy.bool[builtins.bool]] | dtype[integer[Any]]]] | builtins.bool | int | _NestedSequence[builtins.bool | int] | None | tuple[SupportsIndex | slice[Any, Any, Any] | EllipsisType | _SupportsArray[dtype[numpy.bool[builtins.bool]] | dtype[integer[Any]]] | _NestedSequence[_SupportsArray[dtype[numpy.bool[builtins.bool]] | dtype[integer[Any]]]] | builtins.bool | int | _NestedSequence[builtins.bool | int] | None, ...]"  [index]
glass/shells.py:745: error: Incompatible return value type (got "ndarray[tuple[int, ...], dtype[floating[Any]]]", expected "ndarray[tuple[int, ...], dtype[float64]]")  [return-value]
glass/points.py:88: error: Incompatible return value type (got "ndarray[tuple[int, ...], dtype[floating[Any]]]", expected "ndarray[tuple[int, ...], dtype[float64]]")  [return-value]
glass/points.py:110: error: Incompatible return value type (got "ndarray[tuple[int, ...], dtype[floating[Any]]]", expected "ndarray[tuple[int, ...], dtype[float64]]")  [return-value]
glass/points.py:416: error: Incompatible types in assignment (expression has type "ndarray[tuple[int, ...], dtype[floating[Any]]]", variable has type "ndarray[tuple[int, ...], dtype[float64]]")  [assignment]
Found 12 errors in 3 files (checked 13 source files)

[paddyroddy]

These are really weird. They happened in between #466 & #467. But now even if I downgrade mypy it fails. We need to be careful as I think my initial attempt in #467 broke the tests.