Ensure manylinux release task generates manylinux wheels compatible with older pip versions

auditwheel now produces wheels with new "manylinux_x_y" tags according to PEP 600. Installing these wheels requires pip pip >= 20.3. We need to ensure that our manylinux release task generates manylinux wheels compatible with older pip versions.

https://github.com/pypa/auditwheel/issues/314