fix: changed python version to python3 in CI/CD

.gitlab-ci.yml

examples/python/bench.py

examples/python/pocket.py

examples/python/pocket_pyboy.py

examples/python/pocket_pyboy_iface.py

examples/python/pyboy/gamewrapper_tetris.py

setup.py

src/python/boytacean/__init__.py

src/python/boytacean/boytacean.pyi

src/python/boytacean/gb.py

src/python/boytacean/graphics.py

src/python/boytacean/palettes.py

src/python/boytacean/pyboy.py

src/python/boytacean/test/base.py

src/python/boytacean/video.py