python3Packages.aioxmpp: fix meta.changelog (#514586)

  meta = {

    description = "Pure-python XMPP library for asyncio";

    homepage = "https://codeberg.org/jssfr/aioxmpp";

    changelog = "https://codeberg.org/jssfr/aioxmpp/blob/${src.rev}/docs/api/changelog.rst";

    changelog = "https://codeberg.org/jssfr/aioxmpp/src/tag/${src.tag}/docs/api/changelog.rst";

    license = lib.licenses.lgpl3Plus;

    maintainers = with lib.maintainers; [ dotlambda ];

  };