solver build instead of package set

Co-authored-by: Fabrizio Ferrai <[email protected]>

spago.yaml

@@ -23,12 +23,4 @@ package:
       - partial
       - spec
 
-workspace:
-  extraPackages:
-    assert: 6.0.0
-    console: 6.0.0
-    partial: 4.0.0
-    spec: 8.0.0
-    spec-node: 0.0.2
-  packageSet:
-    registry: 55.1.0
+workspace: {}