[CodingInAVan]

Bumps the version to 1.3.0rc6. This commit touches only CMakeLists.txt GPUFL_VERSION_SUFFIX, pyproject.toml and python/gpufl/__init__.py. release.yml rewrites only the numeric CMake version from the tag, so the suffix has to be committed.

rc6 contains:

• Capture PTX that programs load at run time #174: PTX that a program hands to the driver at run time is captured, from cuModuleLoadData, cuModuleLoadDataEx and cuLinkAddData, after a successful load. Rust (cuda-oxide) sessions get PTX beside SASS, as CUDA C++ sessions already do. reset() now clears the PTX state, so a later session in the same process runs cuobjdump again.

After merge: tag the merge commit v1.3.0rc6. That publishes to PyPI and the Jupyter image.