ESOP'25 fix

OGS development at the time of submission of the ESOP'25 "An abstract, certified account of operational game semantics".

Bugfix: add REQUIREMENTS file as per artifact submission guidelines.

ESOP'25

OGS development at the time of submission of the ESOP'25 "An abstract, certified account of operational game semantics". Archived at doi:10.5281/zenodo.14627318 together with the prebuilt docker image.