Revert "lisp/ox-latex: Omit empty date"

This reverts commit a753d0d. Omitting \date in the LaTeX source makes LaTeX print today's date by default, which is not consistent with :with-date export option. See https://list.orgmode.org/m2v8rdguil.fsf@gmail.com/T/#t

Author: yantar92

lisp/ox-latex.el

@@ -1980,8 +1980,7 @@ holding export options."
  ((or author email) (format "\\author{%s}\n" (or author email)))))
  ;; Date.
  (let ((date (and (plist-get info :with-date) (org-export-get-date info))))
- (when date
- (format "\\date{%s}\n" (org-export-data date info))))
+ (format "\\date{%s}\n" (org-export-data date info)))
  ;; Title and subtitle.
  (let* ((subtitle (plist-get info :subtitle))
  (formatted-subtitle