strftime deprecation will break get_local_date

[npr-gh]

strftime is deprecated and will be removed once PHP9 comes out.

This function is currently exposed via effectively a thin wrapper; the get_local_date function within Item.php

 public function get_local_date($date_format = '%c')
        {
                if (!$date_format)
                {
                        return $this->sanitize($this->get_date(''), SIMPLEPIE_CONSTRUCT_TEXT);
                }
                elseif (($date = $this->get_date('U')) !== null && $date !== false)
                {
                        return strftime($date_format, $date);
                }

                return null;
        }

Unfortunately the replacements (datetime.format which allows for explicit formatting or intldateformatter.format which will take a DateTime and a Locale and format it correctly for you) do not have compatible format signatures.

[jtojnar]

See #799 (review)