ox-html: Remove references to Github

* lisp/ox-html.el (org-html-htmlize-generate-css):
(org-html-fontify-code): Remove references to Github.

Fixes: bug#32722

lisp/ox-html.el

@@ -1749,8 +1749,8 @@ If you then set `org-html-htmlize-output-type' to `css', calls
 to the function `org-html-htmlize-region-for-paste' will
 produce code that uses these same face definitions."
   (interactive)
-  (or (require 'htmlize nil t)
-      (error "Please install htmlize from https://github.com/hniksic/emacs-htmlize"))
+  (unless (require 'htmlize nil t)
+    (error "htmlize library missing.  Aborting"))
   (and (get-buffer "*html*") (kill-buffer "*html*"))
   (with-temp-buffer
     (let ((fl (face-list))
@@ -2168,12 +2168,10 @@ is the language used for CODE, as a string, or nil."
      ;; Plain text explicitly set.
      ((not org-html-htmlize-output-type) (org-html-encode-plain-text code))
      ;; No htmlize library or an inferior version of htmlize.
-     ((not (and (or (require 'htmlize nil t)
-		    (error "Please install htmlize from \
-https://github.com/hniksic/emacs-htmlize"))
-		(fboundp 'htmlize-region-for-paste)))
+     ((not (progn (require 'htmlize nil t)
+		  (fboundp 'htmlize-region-for-paste)))
       ;; Emit a warning.
-      (message "Cannot fontify src block (htmlize.el >= 1.34 required)")
+      (message "Cannot fontify source block (htmlize.el >= 1.34 required)")
       (org-html-encode-plain-text code))
      (t
       ;; Map language