Added "random seed" to the magic startup file so that the behavior
of adding unique prefixes to vendor GDS dumps is truly randomized.

sky130/magic/sky130.magicrc

diff --git a/sky130/magic/sky130.magicrc b/sky130/magic/sky130.magicrc
index c0828aa..0875315 100644
--- a/sky130/magic/sky130.magicrc
+++ b/sky130/magic/sky130.magicrc
@@ -14,6 +14,9 @@
 
 # drc off
 drc euclidean on
+# Change this to a fixed number for repeatable behavior with GDS writes
+# e.g., "random seed 12345"
+catch {random seed}
 
 # Allow override of PDK path from environment variable PDKPATH
 if {[catch {set PDKPATH $env(PDKPATH)}]} {