chore(org-mode): switch to built-in org-mode

The upstream org-mode package seems to have changes on a daily basis,
and org-mode is one of the slowest packages to install. This should
avoid those long wait times.

modules/org-mode/siren-org-mode.el

@@ -13,6 +13,7 @@
 (require 'siren-smartparens)
 
 (use-package org
+  :straight (:type built-in)
   :bind
   (:map org-mode-map
         ("C-j" . org-return-indent)

straight/versions/default.el

@@ -122,7 +122,6 @@
  ("ns-auto-titlebar" . "60273e764bf8d95abc40dd2fdc23af87ea9ee33b")
  ("ob-http" . "b1428ea2a63bcb510e7382a1bf5fe82b19c104a7")
  ("ob-mermaid" . "cca09b64eff689d8bb15a77de9d4c7fe9845a1f9")
- ("org" . "94d1753ec8b171442f0e789ca38beee2415198b0")
  ("osx-trash" . "0f1dc052d0a750b8c75f14530a4897f5d4324b4e")
  ("ox-gfm" . "99f93011b069e02b37c9660b8fcb45dab086a07f")
  ("ox-pandoc" . "aa37dc7e94213d4ebedb85c384c1ba35007da18e")