refactor: add basic inspect

TODO: Replace this with a better inspect that properly handles class names etc.

lib/comfpile/artefact.rb

@@ -282,8 +282,11 @@ module Comfpile
             @running = false
         end
 
-        def to_s
+        def inspect
             "#<Compfile::Artefact #{@stage} #{@target}>"
         end
+        def to_s
+            inspect
+        end
     end
 end