ci: change Linux x86 Docker images to manylinux2010
ci: change Linux x86 Docker images to manylinux2010

This now matches the 64-bit builds. I'm not sure how things were out
of sync.

indygreg/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard