Fixing including right pm3 file from spice corner files. Fixes https://github.com/google/skywater-pdk/issues/228. Signed-off-by: Stefan Schippers <schippes@mazinga.lan> Signed-off-by: Tim Edwards <tim@opencircuitdesign.com> Signed-off-by: Tim 'mithro' Ansell <me@mith.ro>