gpu/README.md compatibility matrix mismatch

[dialogbox]

https://github.com/GoogleCloudDataproc/initialization-actions/blob/main/gpu/README.md#default-versions

This table says 2.2-ubuntu22 is tested for CUDA 11.8.
However, the code doesn't seem to agree on this.

initialization-actions/gpu/install_gpu_driver.sh

Lines 1061 to 1063 in 84c2cba

	if ( is_cuda11 && is_ubuntu22 ) ; then
	echo "Kernel modules cannot be compiled for CUDA 11 on ${_shortname}"
	exit 1