docs: Bump up Netlify Python version to 3.8
docs: Bump up Netlify Python version to 3.8

Python 3.7 is no longer supported.

Ref: https://github.com/netlify/build-image/blob/focal/included_software.md

Signed-off-by: Michi Mutsuzaki <a75494f12f73453b2bd75573f87b8f21fcc50565@isovalent.com>

cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium