Update License to match SPDX standard

[PabloJomer]

Update the license to simplify compliance work.

https://spdx.org/licenses/BSD-2-Clause.html

[fabiosantoscode]

Hello there!

Sorry I didn't reply earlier.

I viewed this in a diff viewer, and noticed the text is different. The words "OR CONTRIBUTORS" are new. I have to figure out if this is something I can do without written permission.

[PabloJomer]

I completely understand. Licenses tend to be more complicated than you might think. In my view this just broadens the disclaimer to include more people which should most likely be fine.