Update gitmodules

Signed-off-by: David Shah <dave@ds0.me>
diff --git a/.gitmodules b/.gitmodules
index e837083..d18f724 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "database"]
 	path = database
-	url = https://github.com/SymbiFlow/prjtrellis-db
+	url = https://github.com/YosysHQ/prjtrellis-db