Update customize-package-emacs-version-alist

* lisp/org.el (customize-package-emacs-version-alist): Map Org 9.3 to
Emacs 27.1.

lisp/org.el

@@ -4955,7 +4955,8 @@ The following commands are available:
 		   ("8.3" . "26.1")
 		   ("9.0" . "26.1")
 		   ("9.1" . "26.1")
-		   ("9.2" . "27.1")))
+		   ("9.2" . "27.1")
+		   ("9.3" . "27.1")))
 
 (defvar org-mode-transpose-word-syntax-table
   (let ((st (make-syntax-table text-mode-syntax-table)))