ox-html: Fix author meta-data

* lisp/ox-html.el (org-html--build-meta-info): Prevent duplicates in
author meta-data.

lisp/ox-html.el

@@ -1853,13 +1853,8 @@ INFO is a plist used as a communication channel."
          (title (if (org-string-nw-p title) title "‎"))
          (author (and (plist-get info :with-author)
                       (let ((auth (plist-get info :author)))
-                        (and auth
-                             ;; Return raw Org syntax, skipping non
-                             ;; exportable objects.
-                             (org-element-interpret-data
-                              (org-element-map auth
-                                  (cons 'plain-text org-element-all-objects)
-                                'identity info))))))
+			;; Return raw Org syntax.
+                        (and auth (org-element-interpret-data auth)))))
          (description (plist-get info :description))
          (keywords (plist-get info :keywords))
          (charset (or (and org-html-coding-system
@@ -1882,7 +1877,7 @@ INFO is a plist used as a communication channel."
       charset) "\n"
      (let ((viewport-options
 	    (cl-remove-if-not (lambda (cell) (org-string-nw-p (cadr cell)))
-			       (plist-get info :html-viewport))))
+			      (plist-get info :html-viewport))))
        (and viewport-options
 	    (concat
 	     (org-html-close-tag