♻️ Favor cl- functions

When requiring `rpgdm.el` and it's "child" packages, I encounter the
following warnings:

> Warning: ‘destructuring-bind’ is an obsolete alias (as of 27.1); use
> ‘cl-destructuring-bind’ instead.
>
> Warning: ‘incf’ is an obsolete alias (as of 27.1); use ‘cl-incf’
> instead.
>
> Warning: ‘decf’ is an obsolete alias (as of 27.1); use ‘cl-decf’
> instead.
>
> Warning: ‘defstruct’ is an obsolete alias (as of 27.1); use
> ‘cl-defstruct’ instead.

Since we've already required the `cl` package, this should be a noop change.

rpgdm-tables-freq.el

@@ -142,7 +142,7 @@ decrement the ROLL value."
            ;; (message "Comparing %d <= %d for %s" roll num-elems tag)
            (if (<= roll num-elems)
                (return tag)
-             (decf roll num-elems))))
+             (cl-decf roll num-elems))))
 
 (ert-deftest rpgdm-tables--find-tag-test ()
   (let ((weighted-tags