Merge branch 'opencl-3' into 'master'

.github/workflows/ci.yml

.gitlab-ci.yml

.test-conda-env-py3.yml

doc/make_constants.py

doc/misc.rst

doc/runtime_const.rst

doc/runtime_memory.rst

doc/runtime_platform.rst

doc/runtime_program.rst

pyopencl/__init__.py

src/wrap_cl.hpp

src/wrap_cl_part_1.cpp

src/wrap_cl_part_2.cpp

src/wrap_constants.cpp