fix the path splitting issue for directory exclusion

site.hs

@@ -56,7 +56,7 @@ isSourceablePath :: FilePath -> Site Bool
 isSourceablePath fp = do
   notSource <- use notSourceDirs
   pure $ (&&) <$> hasSuffix ".md" . last <*> not . any (`elem` notSource) . init $
-    splitPath fp
+    splitDirectories fp
 
 -- | Load the pages from a directory and add them to `pages`.
 sourcePages :: FilePath -> Site ()