[libcxx-commits] [libcxx] [libc++] Bump libc++ runners to include python-venv (PR #189008)

[Louis Dionne via libcxx-commits]

ldionne wrote:

Note that we're currently on the `libcxx-next-runners`, so we'll:

1. Bump `libcxx-runners` (not `next`) to the new Docker image -- that's this commit
2. Switch over the Github action workflow to target `libcxx-runners` instead of `libcxx-next-runners`. (in a future PR)

https://github.com/llvm/llvm-project/pull/189008