Fixed paramval2str type error for non-str lists (With version change)

Same as https://github.com/verybadsoldier/backtrader_plotting/pull/91 , but with version change and changelog

---

Hi, if you have parameter with list of something other than list (e.g. list of dicts), you'll get a error TypeError: sequence item 0: expected str instance, <YOUR_NON_STR_TYPE_HERE> found.

With this fix you'll convert everything to string recursively, thus preserving better text output.

Slightly better than https://github.com/verybadsoldier/backtrader_plotting/pull/88