Updated url to bulk download endpoint that is more stable.

Transition to new backend endpoint.

This version adds financial signals support for the banks and insurances datasets.

This version introduces 2 new datasets: derived figures & ratios for fundamentals (dataset: "derived") and derived figures & ratios for share price related data (dataset: "derived-shareprices").

Reworked publish dates and added a new column "Restated Date" (python shortcut RESTATED_DATE).

https://github.com/SimFin/simfin/blob/master/CHANGELOG.md#version-060-2020-04-12

https://github.com/SimFin/simfin/blob/master/CHANGELOG.md#version-050-2020-03-14

https://github.com/SimFin/simfin/blob/master/CHANGELOG.md#version-040-2020-01-25