bump version to 2.3.15
bump version to 2.3.15

katrinleinweber/podlove-publisher,katrinleinweber/podlove-publisher,podlove/podlove-publisher,podlove/podlove-publisher,podlove/podlove-publisher,katrinleinweber/podlove-publisher,podlove/podlove-publisher,katrinleinweber/podlove-publisher,podlove/podlove-publisher,katrinleinweber/podlove-publisher,podlove/podlove-publisher