Update RTD config to use Python 3.10 and latest rocm-docs-core

[samjwu]

Update RTD config to use Python 3.10 and rocm-docs-core

Summary of proposed changes:

ReadtheDocs will use Python 3.10 instead of Python 3.8 to build docs
    To use newer packages (eg: Sphinx 7)
Doc builds will use latest rocm-docs-core version