Numpy 2.x causes out of bounds error for BitMaskedArray kernels

[ManasviGoyal]

Version of Awkward Array

2.6.3

Description and code to reproduce

Due to the changes to promotion in Numpy 2.x, some tests for BitMaskedArray Python kernels gives:
OverflowError: Python integer 464 out of bounds for uint8

It needs to be explicitly promoted now.

[jpivarski]

Mentioned in #3064 (comment), the specific tests are the ones removed in 2bcb015, namely

awkward_BitMaskedArray_to_ByteMaskedArray test with

                {
                    "error": false,
                    "message": "",
                    "inputs": {
                        "bitmasklength": 2,
                        "frombitmask": [58, 59],
                        "lsb_order": false,
                        "validwhen": false
                    },
                    "outputs": {
                        "tobytemask": [0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1]
                    }
                }

awkward_BitMaskedArray_to_IndexedOptionArray test with

                {
                    "error": false,
                    "message": "",
                    "inputs": {
                        "bitmasklength": 2,
                        "frombitmask": [58, 59],
                        "lsb_order": false,
                        "validwhen": false
                    },
                    "outputs": {
                        "toindex": [0, 1, -1, -1, -1, 5, -1, 7, 8, 9, -1, -1, -1, 13, -1, -1]
                    }
                }