lang/org: improve tab indent in src blocks

I realize org-src-tab-acts-natively exists, but it doesn't work for me.
This little fix (plus the next commit's editorconfig fix) should make
tab act much more reliably in src blocks.

modules/lang/org/autoload/org.el

@@ -298,7 +298,8 @@ with `org-cycle'). Also:
          (ignore-errors (org-demote))
          t)
         ((org-in-src-block-p t)
-         (doom/dumb-indent)
+         (org-babel-do-in-edit-buffer
+          (call-interactively #'indent-for-tab-command))
          t)))
 
 ;;;###autoload