add tobytes to support numpy>=2.3.0

[chrishavlin]

Close #149

Went through and added a tobytes option wherever tostring was being used to support numpy >= 2.3.0, which removed the deprecated tostring method for arrays.

Let me know if this needs any additional tests.

[ChrisBarker-NOAA]

numpy has had tobytes for a long time -- I think we can simply replace tostring with tobytes, rather than checking for existence.

certainly numpy 2 has always had it.

Also -- I think you want to do PRs against the develop branch -- master is pretty old.

[chrishavlin]

thanks, changed the PR target branch!

And yeah, tobytes has been around a long time. But I don't know the pyopengl codebase well and it wasn't obvious to me what ranges in numpy and Python are targeted for support. I'll go ahead and update it.