Additional changes to the spectre_to_spice.py script in support of
onboarding the continuous SPICE models. Also: Added "-j" option
to "make timing" for the PDK repository download and update, so
that "make timing", which takes a long time, can run a lot faster.
diff --git a/sky130/custom/scripts/pdk_update.sh b/sky130/custom/scripts/pdk_update.sh
index c6bb970..dd8b66b 100755
--- a/sky130/custom/scripts/pdk_update.sh
+++ b/sky130/custom/scripts/pdk_update.sh
@@ -28,4 +28,4 @@
# Regenerate liberty files
echo "Regenerating liberty timing files"
-make timing
+make -j$(nproc) timing