fix: comply with boost-histogram 1.4.0

[ikrommyd]

boost-histogram 1.4.0 now states that "filling an integer-based axis requires an integer array - a floating point array is disallowed (a single float was always disallowed), due to issues with rounding around 0". So, I add dtype=int to all ak.zeros_like and np.arange in analysis_tools.

[lgray]

There's a broken test from awkward right now. I'll check that none of the associated tests for analysis tools are broken by this.

[ikrommyd]

I've only touched analysis_tools.py. I control-F'ed in vscode but couldn't find another such instance in the source code. Tests pass locally so unless we encounter another apple silicon vs x86 case it should be good.

[ikrommyd]

Touched a few more minor stuff since we're here.