update json serialization in build-dep job

Author: leighmcculloch

.github/workflows/newbuild.yml

@@ -147,7 +147,7 @@ jobs:
 
   build-dep:
     needs: [setup, prepare]
-    if: needs.prepare.outputs.deps-to-build != fromJSON([])
+    if: needs.prepare.outputs.deps-to-build != toJSON([])
     strategy:
       matrix:
         dep: ${{ fromJSON(needs.prepare.outputs.deps-to-build) }}